19640656 has 40 divisors (see below), whose sum is σ = 44997120. Its totient is φ = 8125824.

The previous prime is 19640653. The next prime is 19640671. The reversal of 19640656 is 65604691.

It is a super-2 number, since 2×19640656² = 771510736220672, which contains 22 as substring.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19640651) 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 7 ways as a sum of consecutive naturals, for example, 225 + ... + 6271.

It is an arithmetic number, because the mean of its divisors is an integer number (1124928).

Almost surely, 2^19640656 is an apocalyptic number.

19640656 is a gapful number since it is divisible by the number (16) 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 19640656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22498560).

19640656 is an abundant number, since it is smaller than the sum of its proper divisors (25356464).

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

19640656 is a wasteful number, since it uses less digits than its factorization.

19640656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6091 (or 6085 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 19640656 is about 4431.7779727780. Note that the first 3 decimals coincide. The cubic root of 19640656 is about 269.8062441646.

The spelling of 19640656 in words is "nineteen million, six hundred forty thousand, six hundred fifty-six".