81337531 has 24 divisors (see below), whose sum is σ = 92610560. Its totient is φ = 71351280.

The previous prime is 81337523. The next prime is 81337559. The reversal of 81337531 is 13573318.

It is a happy number.

It is not a de Polignac number, because 81337531 - 2³ = 81337523 is a prime.

It is a super-2 number, since 2×81337531² = 13231587898351922, 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 = 81337493 and 81337502.

It is not an unprimeable number, because it can be changed into a prime (81337511) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 640390 + ... + 640516.

Almost surely, 2^81337531 is an apocalyptic number.

81337531 is a deficient number, since it is larger than the sum of its proper divisors (11273029).

81337531 is a wasteful number, since it uses less digits than its factorization.

81337531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295 (or 284 counting only the distinct ones).

The product of its digits is 7560, while the sum is 31.

The square root of 81337531 is about 9018.7322279797. The cubic root of 81337531 is about 433.2750307491.

The spelling of 81337531 in words is "eighty-one million, three hundred thirty-seven thousand, five hundred thirty-one".