99921881 has 2 divisors, whose sum is σ = 99921882. Its totient is φ = 99921880.

The previous prime is 99921847. The next prime is 99921883. The reversal of 99921881 is 18812999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 67897600 + 32024281 = 8240^2 + 5659^2 .

It is a cyclic number.

It is not a de Polignac number, because 99921881 - 2¹⁴ = 99905497 is a prime.

It is a super-2 number, since 2×99921881² = 19968764605156322, which contains 22 as substring.

Together with 99921883, 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 (99921883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49960940 + 49960941.

It is an arithmetic number, because the mean of its divisors is an integer number (49960941).

Almost surely, 2^99921881 is an apocalyptic number.

It is an amenable number.

99921881 is a deficient number, since it is larger than the sum of its proper divisors (1).

99921881 is an equidigital number, since it uses as much as digits as its factorization.

99921881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 47.

The square root of 99921881 is about 9996.0932868796. The cubic root of 99921881 is about 464.0379864486.

It can be divided in two parts, 99 and 921881, that multiplied together give a palindrome (91266219).

The spelling of 99921881 in words is "ninety-nine million, nine hundred twenty-one thousand, eight hundred eighty-one".