81315 has 24 divisors (see below), whose sum is σ = 152880. Its totient is φ = 39744.

The previous prime is 81307. The next prime is 81331. The reversal of 81315 is 51318.

81315 = 73² + 74² + ... + 85².

It is a happy number.

It is not a de Polignac number, because 81315 - 2³ = 81307 is a prime.

It is a super-2 number, since 2×81315² = 13224258450, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 516 + ... + 654.

It is an arithmetic number, because the mean of its divisors is an integer number (6370).

2⁸¹³¹⁵ is an apocalyptic number.

81315 is a deficient number, since it is larger than the sum of its proper divisors (71565).

81315 is a wasteful number, since it uses less digits than its factorization.

81315 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163 (or 160 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 81315 is about 285.1578510229. The cubic root of 81315 is about 43.3235020432.

It can be divided in two parts, 813 and 15, that added together give a palindrome (828).

The spelling of 81315 in words is "eighty-one thousand, three hundred fifteen".