81931547516 has 24 divisors (see below), whose sum is σ = 176467949280. Its totient is φ = 32412480192.

The previous prime is 81931547501. The next prime is 81931547521. The reversal of 81931547516 is 61574513918.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 112542971 + ... + 112543698.

It is an arithmetic number, because the mean of its divisors is an integer number (7352831220).

Almost surely, 2^81931547516 is an apocalyptic number.

It is an amenable number.

81931547516 is an abundant number, since it is smaller than the sum of its proper divisors (94536401764).

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

81931547516 is a wasteful number, since it uses less digits than its factorization.

81931547516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225086693 (or 225086691 counting only the distinct ones).

The product of its digits is 907200, while the sum is 50.

The spelling of 81931547516 in words is "eighty-one billion, nine hundred thirty-one million, five hundred forty-seven thousand, five hundred sixteen".