81431571 has 16 divisors (see below), whose sum is σ = 117089280. Its totient is φ = 50042400.

The previous prime is 81431563. The next prime is 81431579. The reversal of 81431571 is 17513418.

It is an interprime number because it is at equal distance from previous prime (81431563) and next prime (81431579).

It is not a de Polignac number, because 81431571 - 2³ = 81431563 is a prime.

It is a super-2 number, since 2×81431571² = 13262201511056082, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81431579) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55396 + ... + 56846.

It is an arithmetic number, because the mean of its divisors is an integer number (7318080).

Almost surely, 2^81431571 is an apocalyptic number.

81431571 is a deficient number, since it is larger than the sum of its proper divisors (35657709).

81431571 is a wasteful number, since it uses less digits than its factorization.

81431571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2906.

The product of its digits is 3360, while the sum is 30.

The square root of 81431571 is about 9023.9443149878. The cubic root of 81431571 is about 433.4419462787.

Adding to 81431571 its reverse (17513418), we get a palindrome (98944989).

It can be divided in two parts, 814 and 31571, that added together give a triangular number (32385 = T₂₅₄).

The spelling of 81431571 in words is "eighty-one million, four hundred thirty-one thousand, five hundred seventy-one".