81719572625 has 16 divisors (see below), whose sum is σ = 103657938384. Its totient is φ = 64303920000.

The previous prime is 81719572619. The next prime is 81719572643. The reversal of 81719572625 is 52627591718.

It can be written as a sum of positive squares in 8 ways, for example, as 37390796689 + 44328775936 = 193367^2 + 210544^2 .

It is not a de Polignac number, because 81719572625 - 2⁸ = 81719572369 is a prime.

It is a Duffinian 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, 5351036 + ... + 5366285.

It is an arithmetic number, because the mean of its divisors is an integer number (6478621149).

Almost surely, 2^81719572625 is an apocalyptic number.

It is an amenable number.

81719572625 is a deficient number, since it is larger than the sum of its proper divisors (21938365759).

81719572625 is a wasteful number, since it uses less digits than its factorization.

81719572625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10717397 (or 10717387 counting only the distinct ones).

The product of its digits is 2116800, while the sum is 53.

The spelling of 81719572625 in words is "eighty-one billion, seven hundred nineteen million, five hundred seventy-two thousand, six hundred twenty-five".