19664540 has 96 divisors (see below), whose sum is σ = 51093504. Its totient is φ = 6209280.

The previous prime is 19664539. The next prime is 19664549. The reversal of 19664540 is 4546691.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 19664540.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19664549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 99722 + ... + 99918.

It is an arithmetic number, because the mean of its divisors is an integer number (532224).

Almost surely, 2^19664540 is an apocalyptic number.

19664540 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 19664540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25546752).

19664540 is an abundant number, since it is smaller than the sum of its proper divisors (31428964).

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

19664540 is a wasteful number, since it uses less digits than its factorization.

19664540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267 (or 265 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 19664540 is about 4434.4717836514. The cubic root of 19664540 is about 269.9155657339.

The spelling of 19664540 in words is "nineteen million, six hundred sixty-four thousand, five hundred forty".