99391531 has 2 divisors, whose sum is σ = 99391532. Its totient is φ = 99391530.

The previous prime is 99391529. The next prime is 99391561. The reversal of 99391531 is 13519399.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 99391531 - 2¹ = 99391529 is a prime.

It is a super-2 number, since 2×99391531² = 19757352869047922, which contains 22 as substring.

Together with 99391529, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (99391561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49695765 + 49695766.

It is an arithmetic number, because the mean of its divisors is an integer number (49695766).

Almost surely, 2^99391531 is an apocalyptic number.

99391531 is a deficient number, since it is larger than the sum of its proper divisors (1).

99391531 is an equidigital number, since it uses as much as digits as its factorization.

99391531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32805, while the sum is 40.

The square root of 99391531 is about 9969.5301293491. The cubic root of 99391531 is about 463.2155464902.

The spelling of 99391531 in words is "ninety-nine million, three hundred ninety-one thousand, five hundred thirty-one".