81293664 has 48 divisors (see below), whose sum is σ = 213902640. Its totient is φ = 27033600.

The previous prime is 81293657. The next prime is 81293671. The reversal of 81293664 is 46639218.

It is an interprime number because it is at equal distance from previous prime (81293657) and next prime (81293671).

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56992 + ... + 58400.

It is an arithmetic number, because the mean of its divisors is an integer number (4456305).

Almost surely, 2^81293664 is an apocalyptic number.

It is an amenable number.

81293664 is an abundant number, since it is smaller than the sum of its proper divisors (132608976).

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

81293664 is a wasteful number, since it uses less digits than its factorization.

81293664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2023 (or 2015 counting only the distinct ones).

The product of its digits is 62208, while the sum is 39.

The square root of 81293664 is about 9016.2999062808. The cubic root of 81293664 is about 433.1971253696.

The spelling of 81293664 in words is "eighty-one million, two hundred ninety-three thousand, six hundred sixty-four".