81320507 has 4 divisors (see below), whose sum is σ = 83303976. Its totient is φ = 79337040.

The previous prime is 81320501. The next prime is 81320527. The reversal of 81320507 is 70502318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 70502318 = 2 ⋅35251159.

It is a cyclic number.

It is not a de Polignac number, because 81320507 - 2¹⁴ = 81304123 is a prime.

It is a super-2 number, since 2×81320507² = 13226049717474098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81320501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 991673 + ... + 991754.

It is an arithmetic number, because the mean of its divisors is an integer number (20825994).

Almost surely, 2^81320507 is an apocalyptic number.

81320507 is a deficient number, since it is larger than the sum of its proper divisors (1983469).

81320507 is a wasteful number, since it uses less digits than its factorization.

81320507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1983468.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 81320507 is about 9017.7883652257. The cubic root of 81320507 is about 433.2448003880.

The spelling of 81320507 in words is "eighty-one million, three hundred twenty thousand, five hundred seven".