21637968665099 has 2 divisors, whose sum is σ = 21637968665100. Its totient is φ = 21637968665098.

The previous prime is 21637968665057. The next prime is 21637968665113. The reversal of 21637968665099 is 99056686973612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21637968665099 - 2¹² = 21637968661003 is a prime.

It is not a weakly prime, because it can be changed into another prime (21637968665039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10818984332549 + 10818984332550.

It is an arithmetic number, because the mean of its divisors is an integer number (10818984332550).

Almost surely, 2^{21637968665099} is an apocalyptic number.

21637968665099 is a deficient number, since it is larger than the sum of its proper divisors (1).

21637968665099 is an equidigital number, since it uses as much as digits as its factorization.

21637968665099 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1587237120, while the sum is 77.

The spelling of 21637968665099 in words is "twenty-one trillion, six hundred thirty-seven billion, nine hundred sixty-eight million, six hundred sixty-five thousand, ninety-nine".