81431359 has 4 divisors (see below), whose sum is σ = 85717240. Its totient is φ = 77145480.

The previous prime is 81431341. The next prime is 81431369. The reversal of 81431359 is 95313418.

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 81431359 - 2⁹ = 81430847 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81431369) 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, 2142912 + ... + 2142949.

It is an arithmetic number, because the mean of its divisors is an integer number (21429310).

Almost surely, 2^81431359 is an apocalyptic number.

81431359 is a deficient number, since it is larger than the sum of its proper divisors (4285881).

81431359 is a wasteful number, since it uses less digits than its factorization.

81431359 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4285880.

The product of its digits is 12960, while the sum is 34.

The square root of 81431359 is about 9023.9325684537. The cubic root of 81431359 is about 433.4415701356.

The spelling of 81431359 in words is "eighty-one million, four hundred thirty-one thousand, three hundred fifty-nine".