99915581 has 2 divisors, whose sum is σ = 99915582. Its totient is φ = 99915580.

The previous prime is 99915553. The next prime is 99915589. The reversal of 99915581 is 18551999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71132356 + 28783225 = 8434^2 + 5365^2 .

It is a cyclic number.

It is not a de Polignac number, because 99915581 - 2¹⁰ = 99914557 is a prime.

It is a super-2 number, since 2×99915581² = 19966246653135122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99915589) 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 as a sum of consecutive naturals, namely, 49957790 + 49957791.

It is an arithmetic number, because the mean of its divisors is an integer number (49957791).

Almost surely, 2^99915581 is an apocalyptic number.

It is an amenable number.

99915581 is a deficient number, since it is larger than the sum of its proper divisors (1).

99915581 is an equidigital number, since it uses as much as digits as its factorization.

99915581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145800, while the sum is 47.

The square root of 99915581 is about 9995.7781588028. The cubic root of 99915581 is about 464.0282338275.

The spelling of 99915581 in words is "ninety-nine million, nine hundred fifteen thousand, five hundred eighty-one".