191579599921 has 2 divisors, whose sum is σ = 191579599922. Its totient is φ = 191579599920.

The previous prime is 191579599907. The next prime is 191579600081. The reversal of 191579599921 is 129995975191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 154700622400 + 36878977521 = 393320^2 + 192039^2 .

It is a cyclic number.

It is not a de Polignac number, because 191579599921 - 2⁵ = 191579599889 is a prime.

It is not a weakly prime, because it can be changed into another prime (191579599901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95789799960 + 95789799961.

It is an arithmetic number, because the mean of its divisors is an integer number (95789799961).

Almost surely, 2^191579599921 is an apocalyptic number.

It is an amenable number.

191579599921 is a deficient number, since it is larger than the sum of its proper divisors (1).

191579599921 is an equidigital number, since it uses as much as digits as its factorization.

191579599921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20667150, while the sum is 67.

The spelling of 191579599921 in words is "one hundred ninety-one billion, five hundred seventy-nine million, five hundred ninety-nine thousand, nine hundred twenty-one".