21012001291 has 2 divisors, whose sum is σ = 21012001292. Its totient is φ = 21012001290.

The previous prime is 21012001273. The next prime is 21012001327. The reversal of 21012001291 is 19210021012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21012001291 - 2⁵ = 21012001259 is a prime.

It is not a weakly prime, because it can be changed into another prime (21012001211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506000645 + 10506000646.

It is an arithmetic number, because the mean of its divisors is an integer number (10506000646).

Almost surely, 2^21012001291 is an apocalyptic number.

21012001291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012001291 is an equidigital number, since it uses as much as digits as its factorization.

21012001291 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 21012001291 in words is "twenty-one billion, twelve million, one thousand, two hundred ninety-one".