16665840 has 120 divisors (see below), whose sum is σ = 56871360. Its totient is φ = 4372992.

The previous prime is 16665839. The next prime is 16665841. The reversal of 16665840 is 4856661.

16665840 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

It is an interprime number because it is at equal distance from previous prime (16665839) and next prime (16665841).

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 16665795 and 16665804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16665841) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 56734 + ... + 57026.

It is an arithmetic number, because the mean of its divisors is an integer number (473928).

Almost surely, 2^16665840 is an apocalyptic number.

16665840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 16665840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28435680).

16665840 is an abundant number, since it is smaller than the sum of its proper divisors (40205520).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16665840 is a wasteful number, since it uses less digits than its factorization.

16665840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391 (or 382 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 16665840 is about 4082.3816578071. The cubic root of 16665840 is about 255.4322541783.

It can be divided in two parts, 16 and 665840, that added together give a square (665856 = 816²).

The spelling of 16665840 in words is "sixteen million, six hundred sixty-five thousand, eight hundred forty".