19651887972025 has 9 divisors (see below), whose sum is σ = 24368368570221. Its totient is φ = 15721492645440.

The previous prime is 19651887972019. The next prime is 19651887972043. The reversal of 19651887972025 is 52027978815691.

The square root of 19651887972025 is 4433045.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 554603410089 + 19097284561936 = 744717^2 + 4370044^2 .

It is a de Polignac number, because none of the positive numbers 2^k-19651887972025 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 21721921 + ... + 22608529.

Almost surely, 2^{19651887972025} is an apocalyptic number.

19651887972025 is the 4433045-th square number.

19651887972025 is the 2216523-rd centered octagonal number.

It is an amenable number.

19651887972025 is a deficient number, since it is larger than the sum of its proper divisors (4716480598196).

19651887972025 is an frugal number, since it uses more digits than its factorization.

19651887972025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773228 (or 886614 counting only the distinct ones).

The product of its (nonzero) digits is 152409600, while the sum is 70.

The spelling of 19651887972025 in words is "nineteen trillion, six hundred fifty-one billion, eight hundred eighty-seven million, nine hundred seventy-two thousand, twenty-five".