81831537 has 48 divisors (see below), whose sum is σ = 131788800. Its totient is φ = 48716640.

The previous prime is 81831527. The next prime is 81831551. The reversal of 81831537 is 73513818.

It is not a de Polignac number, because 81831537 - 2⁴ = 81831521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81831517) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 227764 + ... + 228122.

It is an arithmetic number, because the mean of its divisors is an integer number (2745600).

Almost surely, 2^81831537 is an apocalyptic number.

It is an amenable number.

81831537 is a deficient number, since it is larger than the sum of its proper divisors (49957263).

81831537 is a wasteful number, since it uses less digits than its factorization.

81831537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458 (or 455 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 81831537 is about 9046.0785426615. The cubic root of 81831537 is about 434.1504306263.

The spelling of 81831537 in words is "eighty-one million, eight hundred thirty-one thousand, five hundred thirty-seven".