99981531 has 48 divisors (see below), whose sum is σ = 163363200. Its totient is φ = 58496256.

The previous prime is 99981523. The next prime is 99981547. The reversal of 99981531 is 13518999.

It is not a de Polignac number, because 99981531 - 2³ = 99981523 is a prime.

It is a super-2 number, since 2×99981531² = 19992613082207922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (99981521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 267861 + ... + 268233.

It is an arithmetic number, because the mean of its divisors is an integer number (3403400).

Almost surely, 2^99981531 is an apocalyptic number.

99981531 is a deficient number, since it is larger than the sum of its proper divisors (63381669).

99981531 is a wasteful number, since it uses less digits than its factorization.

99981531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500 (or 497 counting only the distinct ones).

The product of its digits is 87480, while the sum is 45.

The square root of 99981531 is about 9999.0765073581. The cubic root of 99981531 is about 464.1303064339.

The spelling of 99981531 in words is "ninety-nine million, nine hundred eighty-one thousand, five hundred thirty-one".