19901972765 has 16 divisors (see below), whose sum is σ = 24033715200. Its totient is φ = 15820782912.

The previous prime is 19901972747. The next prime is 19901972771. The reversal of 19901972765 is 56727910991.

It is a cyclic number.

It is not a de Polignac number, because 19901972765 - 2¹⁰ = 19901971741 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19901972765.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1879556 + ... + 1890114.

It is an arithmetic number, because the mean of its divisors is an integer number (1502107200).

Almost surely, 2^19901972765 is an apocalyptic number.

It is an amenable number.

19901972765 is a deficient number, since it is larger than the sum of its proper divisors (4131742435).

19901972765 is a wasteful number, since it uses less digits than its factorization.

19901972765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12916.

The product of its (nonzero) digits is 2143260, while the sum is 56.

The spelling of 19901972765 in words is "nineteen billion, nine hundred one million, nine hundred seventy-two thousand, seven hundred sixty-five".