81099531 has 6 divisors (see below), whose sum is σ = 117143780. Its totient is φ = 54066348.

The previous prime is 81099527. The next prime is 81099607. The reversal of 81099531 is 13599018.

It is a happy number.

It is not a de Polignac number, because 81099531 - 2² = 81099527 is a prime.

It is a super-2 number, since 2×81099531² = 13154267856839922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81099331) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4505521 + ... + 4505538.

Almost surely, 2^81099531 is an apocalyptic number.

81099531 is a deficient number, since it is larger than the sum of its proper divisors (36044249).

81099531 is a wasteful number, since it uses less digits than its factorization.

81099531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9011065 (or 9011062 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 81099531 is about 9005.5278024111. The cubic root of 81099531 is about 432.8520189758.

The spelling of 81099531 in words is "eighty-one million, ninety-nine thousand, five hundred thirty-one".