19656764640 has 384 divisors, whose sum is σ = 73461427200. Its totient is φ = 4894525440.

The previous prime is 19656764629. The next prime is 19656764653. The reversal of 19656764640 is 4646765691.

19656764640 is a `hidden beast` number, since 19 + 6 + 567 + 6 + 4 + 64 + 0 = 666.

It is a super-2 number, since 2×19656764640² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5825994 + ... + 5829366.

It is an arithmetic number, because the mean of its divisors is an integer number (191305800).

Almost surely, 2^19656764640 is an apocalyptic number.

19656764640 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 19656764640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36730713600).

19656764640 is an abundant number, since it is smaller than the sum of its proper divisors (53804662560).

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

19656764640 is a wasteful number, since it uses less digits than its factorization.

19656764640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3487 (or 3473 counting only the distinct ones).

The product of its (nonzero) digits is 6531840, while the sum is 54.

The spelling of 19656764640 in words is "nineteen billion, six hundred fifty-six million, seven hundred sixty-four thousand, six hundred forty".