19721959056 has 50 divisors (see below), whose sum is σ = 57081075062. Its totient is φ = 6573985920.

The previous prime is 19721958967. The next prime is 19721959057. The reversal of 19721959056 is 65095912791.

It can be written as a sum of positive squares in only one way, i.e., 18527565456 + 1194393600 = 136116^2 + 34560^2 .

It is a super-3 number, since 3×19721959056³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

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

It is a junction number, because it is equal to n+sod(n) for n = 19721958993 and 19721959011.

It is not an unprimeable number, because it can be changed into a prime (19721959057) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 7607485 + ... + 7610076.

Almost surely, 2^19721959056 is an apocalyptic number.

19721959056 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

19721959056 is an abundant number, since it is smaller than the sum of its proper divisors (37359116006).

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

19721959056 is a wasteful number, since it uses less digits than its factorization.

19721959056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15217581 (or 15217566 counting only the distinct ones).

The product of its (nonzero) digits is 1530900, while the sum is 54.

The spelling of 19721959056 in words is "nineteen billion, seven hundred twenty-one million, nine hundred fifty-nine thousand, fifty-six".