99381331921 has 2 divisors, whose sum is σ = 99381331922. Its totient is φ = 99381331920.

The previous prime is 99381331913. The next prime is 99381331939. The reversal of 99381331921 is 12913318399.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 97578140625 + 1803191296 = 312375^2 + 42464^2 .

It is a cyclic number.

It is not a de Polignac number, because 99381331921 - 2³ = 99381331913 is a prime.

It is not a weakly prime, because it can be changed into another prime (99381331901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49690665960 + 49690665961.

It is an arithmetic number, because the mean of its divisors is an integer number (49690665961).

Almost surely, 2^99381331921 is an apocalyptic number.

It is an amenable number.

99381331921 is a deficient number, since it is larger than the sum of its proper divisors (1).

99381331921 is an equidigital number, since it uses as much as digits as its factorization.

99381331921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 314928, while the sum is 49.

The spelling of 99381331921 in words is "ninety-nine billion, three hundred eighty-one million, three hundred thirty-one thousand, nine hundred twenty-one".