16665640 has 32 divisors (see below), whose sum is σ = 37631880. Its totient is φ = 6642432.

The previous prime is 16665637. The next prime is 16665643. The reversal of 16665640 is 4656661.

16665640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (16665637) and next prime (16665643).

It can be written as a sum of positive squares in 4 ways, for example, as 9278116 + 7387524 = 3046^2 + 2718^2 .

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 16665596 and 16665605.

It is not an unprimeable number, because it can be changed into a prime (16665643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14362 + ... + 15478.

Almost surely, 2^16665640 is an apocalyptic number.

16665640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16665640 is an abundant number, since it is smaller than the sum of its proper divisors (20966240).

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

16665640 is a wasteful number, since it uses less digits than its factorization.

16665640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1501 (or 1497 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 16665640 is about 4082.3571622287. The cubic root of 16665640 is about 255.4312323945.

The spelling of 16665640 in words is "sixteen million, six hundred sixty-five thousand, six hundred forty".