81012864 has 64 divisors (see below), whose sum is σ = 217211040. Its totient is φ = 26750976.

The previous prime is 81012853. The next prime is 81012881. The reversal of 81012864 is 46821018.

It is a tau number, because it is divible by the number of its divisors (64).

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, 42459 + ... + 44325.

Almost surely, 2^81012864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81012864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108605520).

81012864 is an abundant number, since it is smaller than the sum of its proper divisors (136198176).

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

81012864 is a wasteful number, since it uses less digits than its factorization.

81012864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1997 (or 1985 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 81012864 is about 9000.7146382940. The cubic root of 81012864 is about 432.6977749396.

The spelling of 81012864 in words is "eighty-one million, twelve thousand, eight hundred sixty-four".