81355715 has 16 divisors (see below), whose sum is σ = 116425728. Its totient is φ = 53360736.

The previous prime is 81355697. The next prime is 81355717. The reversal of 81355715 is 51755318.

It is not a de Polignac number, because 81355715 - 2²² = 77161411 is a prime.

It is a super-2 number, since 2×81355715² = 13237504726322450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81355717) 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, 49727 + ... + 51336.

It is an arithmetic number, because the mean of its divisors is an integer number (7276608).

Almost surely, 2^81355715 is an apocalyptic number.

81355715 is a deficient number, since it is larger than the sum of its proper divisors (35070013).

81355715 is a wasteful number, since it uses less digits than its factorization.

81355715 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101098.

The product of its digits is 21000, while the sum is 35.

The square root of 81355715 is about 9019.7402955961. The cubic root of 81355715 is about 433.3073163210.

The spelling of 81355715 in words is "eighty-one million, three hundred fifty-five thousand, seven hundred fifteen".