21135208667 has 2 divisors, whose sum is σ = 21135208668. Its totient is φ = 21135208666.

The previous prime is 21135208649. The next prime is 21135208687. The reversal of 21135208667 is 76680253112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21135208667 - 2⁶ = 21135208603 is a prime.

It is not a weakly prime, because it can be changed into another prime (21135208607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10567604333 + 10567604334.

It is an arithmetic number, because the mean of its divisors is an integer number (10567604334).

Almost surely, 2^21135208667 is an apocalyptic number.

21135208667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21135208667 is an equidigital number, since it uses as much as digits as its factorization.

21135208667 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 41.

The spelling of 21135208667 in words is "twenty-one billion, one hundred thirty-five million, two hundred eight thousand, six hundred sixty-seven".