81368647 has 16 divisors (see below), whose sum is σ = 88071840. Its totient is φ = 74898432.

The previous prime is 81368593. The next prime is 81368653. The reversal of 81368647 is 74686318.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81368647 is a prime.

It is a super-2 number, since 2×81368647² = 13241713429221218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81368047) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 214504 + ... + 214882.

It is an arithmetic number, because the mean of its divisors is an integer number (5504490).

Almost surely, 2^81368647 is an apocalyptic number.

81368647 is a deficient number, since it is larger than the sum of its proper divisors (6703193).

81368647 is a wasteful number, since it uses less digits than its factorization.

81368647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642.

The product of its digits is 193536, while the sum is 43.

The square root of 81368647 is about 9020.4571391920. The cubic root of 81368647 is about 433.3302740744.

The spelling of 81368647 in words is "eighty-one million, three hundred sixty-eight thousand, six hundred forty-seven".