81897888464 has 20 divisors (see below), whose sum is σ = 181345324704. Its totient is φ = 35099095008.

The previous prime is 81897888461. The next prime is 81897888469. The reversal of 81897888464 is 46488879818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81897888461) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 365615462 + ... + 365615685.

Almost surely, 2^81897888464 is an apocalyptic number.

It is an amenable number.

81897888464 is an abundant number, since it is smaller than the sum of its proper divisors (99447436240).

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

81897888464 is a wasteful number, since it uses less digits than its factorization.

81897888464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 731231162 (or 731231156 counting only the distinct ones).

The product of its digits is 198180864, while the sum is 71.

The spelling of 81897888464 in words is "eighty-one billion, eight hundred ninety-seven million, eight hundred eighty-eight thousand, four hundred sixty-four".