81307615 has 4 divisors (see below), whose sum is σ = 97569144. Its totient is φ = 65046088.

The previous prime is 81307609. The next prime is 81307657. The reversal of 81307615 is 51670318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81307615 - 2³ = 81307607 is a prime.

It is a super-2 number, since 2×81307615² = 13221856513976450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8130757 + ... + 8130766.

It is an arithmetic number, because the mean of its divisors is an integer number (24392286).

Almost surely, 2^81307615 is an apocalyptic number.

81307615 is a deficient number, since it is larger than the sum of its proper divisors (16261529).

81307615 is a wasteful number, since it uses less digits than its factorization.

81307615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16261528.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 81307615 is about 9017.0735274811. The cubic root of 81307615 is about 433.2219046169.

The spelling of 81307615 in words is "eighty-one million, three hundred seven thousand, six hundred fifteen".