99921431 has 2 divisors, whose sum is σ = 99921432. Its totient is φ = 99921430.

The previous prime is 99921413. The next prime is 99921449. The reversal of 99921431 is 13412999.

Together with previous prime (99921413) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (99921413) and next prime (99921449).

It is an emirp because it is prime and its reverse (13412999) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99921431 is a prime.

It is a super-2 number, since 2×99921431² = 19968584746175522, 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 (99921331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49960715 + 49960716.

It is an arithmetic number, because the mean of its divisors is an integer number (49960716).

Almost surely, 2^99921431 is an apocalyptic number.

99921431 is a deficient number, since it is larger than the sum of its proper divisors (1).

99921431 is an equidigital number, since it uses as much as digits as its factorization.

99921431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 38.

The square root of 99921431 is about 9996.0707780607. The cubic root of 99921431 is about 464.0372898464.

The spelling of 99921431 in words is "ninety-nine million, nine hundred twenty-one thousand, four hundred thirty-one".