81431568 has 100 divisors (see below), whose sum is σ = 248166160. Its totient is φ = 25707456.

The previous prime is 81431563. The next prime is 81431579. The reversal of 81431568 is 86513418.

It is a super-2 number, since 2×81431568² = 13262200533877248, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (81431563) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 22971 + ... + 26277.

Almost surely, 2^81431568 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 81431568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124083080).

81431568 is an abundant number, since it is smaller than the sum of its proper divisors (166734592).

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

81431568 is a wasteful number, since it uses less digits than its factorization.

81431568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3346 (or 3331 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 81431568 is about 9023.9441487633. The cubic root of 81431568 is about 433.4419409559.

It can be divided in two parts, 81 and 431568, that added together give a square (431649 = 657²).

The spelling of 81431568 in words is "eighty-one million, four hundred thirty-one thousand, five hundred sixty-eight".