19721720456724 has 96 divisors (see below), whose sum is σ = 56907724930560. Its totient is φ = 5226219619200.

The previous prime is 19721720456719. The next prime is 19721720456747. The reversal of 19721720456724 is 42765402712791.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 302410662 + ... + 302475869.

It is an arithmetic number, because the mean of its divisors is an integer number (592788801360).

Almost surely, 2^{19721720456724} is an apocalyptic number.

It is an amenable number.

19721720456724 is an abundant number, since it is smaller than the sum of its proper divisors (37186004473836).

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

19721720456724 is a wasteful number, since it uses less digits than its factorization.

19721720456724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 604886581 (or 604886579 counting only the distinct ones).

The product of its (nonzero) digits is 11854080, while the sum is 57.

The spelling of 19721720456724 in words is "nineteen trillion, seven hundred twenty-one billion, seven hundred twenty million, four hundred fifty-six thousand, seven hundred twenty-four".