81768738 has 16 divisors (see below), whose sum is σ = 164131200. Its totient is φ = 27157296.

The previous prime is 81768727. The next prime is 81768763. The reversal of 81768738 is 83786718.

It is a super-2 number, since 2×81768738² = 13372253028225288, which contains 22 as substring.

It is a Curzon 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, 22938 + ... + 26261.

It is an arithmetic number, because the mean of its divisors is an integer number (10258200).

Almost surely, 2^81768738 is an apocalyptic number.

81768738 is an abundant number, since it is smaller than the sum of its proper divisors (82362462).

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

81768738 is a wasteful number, since it uses less digits than its factorization.

81768738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49481.

The product of its digits is 451584, while the sum is 48.

The square root of 81768738 is about 9042.6068144092. The cubic root of 81768738 is about 434.0393439100.

The spelling of 81768738 in words is "eighty-one million, seven hundred sixty-eight thousand, seven hundred thirty-eight".