99987131 has 2 divisors, whose sum is σ = 99987132. Its totient is φ = 99987130.

The previous prime is 99987119. The next prime is 99987133. The reversal of 99987131 is 13178999.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 99987131 - 2⁶ = 99987067 is a prime.

It is a super-2 number, since 2×99987131² = 19994852731222322, which contains 22 as substring.

Together with 99987133, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (99987133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49993565 + 49993566.

It is an arithmetic number, because the mean of its divisors is an integer number (49993566).

Almost surely, 2^99987131 is an apocalyptic number.

99987131 is a deficient number, since it is larger than the sum of its proper divisors (1).

99987131 is an equidigital number, since it uses as much as digits as its factorization.

99987131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 47.

The square root of 99987131 is about 9999.3565292973. The cubic root of 99987131 is about 464.1389716382.

It can be divided in two parts, 999871 and 31, that multiplied together give a triangular number (30996001 = T₇₈₇₃).

The spelling of 99987131 in words is "ninety-nine million, nine hundred eighty-seven thousand, one hundred thirty-one".