81899331 has 16 divisors (see below), whose sum is σ = 110896800. Its totient is φ = 53756928.

The previous prime is 81899327. The next prime is 81899341. The reversal of 81899331 is 13399818.

It is a happy number.

It is not a de Polignac number, because 81899331 - 2² = 81899327 is a prime.

It is a super-2 number, since 2×81899331² = 13415000836495122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81899341) 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, 66025 + ... + 67253.

It is an arithmetic number, because the mean of its divisors is an integer number (6931050).

Almost surely, 2^81899331 is an apocalyptic number.

81899331 is a deficient number, since it is larger than the sum of its proper divisors (28997469).

81899331 is a wasteful number, since it uses less digits than its factorization.

81899331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1558.

The product of its digits is 46656, while the sum is 42.

The square root of 81899331 is about 9049.8249154334. The cubic root of 81899331 is about 434.2702893473.

The spelling of 81899331 in words is "eighty-one million, eight hundred ninety-nine thousand, three hundred thirty-one".