81393431 has 8 divisors (see below), whose sum is σ = 93290400. Its totient is φ = 69563808.

The previous prime is 81393427. The next prime is 81393457. The reversal of 81393431 is 13439318.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81393431 - 2² = 81393427 is a prime.

It is a super-2 number, since 2×81393431² = 13249781219903522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81393031) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 14216 + ... + 19101.

It is an arithmetic number, because the mean of its divisors is an integer number (11661300).

Almost surely, 2^81393431 is an apocalyptic number.

81393431 is a deficient number, since it is larger than the sum of its proper divisors (11896969).

81393431 is a wasteful number, since it uses less digits than its factorization.

81393431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33673.

The product of its digits is 7776, while the sum is 32.

The square root of 81393431 is about 9021.8308008962. The cubic root of 81393431 is about 433.3742654957.

The spelling of 81393431 in words is "eighty-one million, three hundred ninety-three thousand, four hundred thirty-one".