81207931 has 8 divisors (see below), whose sum is σ = 93281760. Its totient is φ = 69252288.

The previous prime is 81207899. The next prime is 81207949. The reversal of 81207931 is 13970218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81207931 - 2⁵ = 81207899 is a prime.

It is a super-2 number, since 2×81207931² = 13189456114601522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81207893 and 81207902.

It is not an unprimeable number, because it can be changed into a prime (81207331) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28066 + ... + 30823.

It is an arithmetic number, because the mean of its divisors is an integer number (11660220).

Almost surely, 2^81207931 is an apocalyptic number.

81207931 is a deficient number, since it is larger than the sum of its proper divisors (12073829).

81207931 is a wasteful number, since it uses less digits than its factorization.

81207931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59093.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 81207931 is about 9011.5443182620. The cubic root of 81207931 is about 433.0447873284.

The spelling of 81207931 in words is "eighty-one million, two hundred seven thousand, nine hundred thirty-one".