81288931 has 8 divisors (see below), whose sum is σ = 82567424. Its totient is φ = 80015040.

The previous prime is 81288929. The next prime is 81288947. The reversal of 81288931 is 13988218.

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 81288931 - 2¹ = 81288929 is a prime.

It is a super-2 number, since 2×81288931² = 13215780606245522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81288901) 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, 54526 + ... + 55996.

It is an arithmetic number, because the mean of its divisors is an integer number (10320928).

Almost surely, 2^81288931 is an apocalyptic number.

81288931 is a deficient number, since it is larger than the sum of its proper divisors (1278493).

81288931 is a wasteful number, since it uses less digits than its factorization.

81288931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2301.

The product of its digits is 27648, while the sum is 40.

The square root of 81288931 is about 9016.0374333739. The cubic root of 81288931 is about 433.1887181470.

The spelling of 81288931 in words is "eighty-one million, two hundred eighty-eight thousand, nine hundred thirty-one".