21216401206291 has 2 divisors, whose sum is σ = 21216401206292. Its totient is φ = 21216401206290.

The previous prime is 21216401206283. The next prime is 21216401206337. The reversal of 21216401206291 is 19260210461212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21216401206291 - 2³ = 21216401206283 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21216401206291.

It is not a weakly prime, because it can be changed into another prime (21216401206201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608200603145 + 10608200603146.

It is an arithmetic number, because the mean of its divisors is an integer number (10608200603146).

Almost surely, 2^{21216401206291} is an apocalyptic number.

21216401206291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216401206291 is an equidigital number, since it uses as much as digits as its factorization.

21216401206291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 37.

The spelling of 21216401206291 in words is "twenty-one trillion, two hundred sixteen billion, four hundred one million, two hundred six thousand, two hundred ninety-one".