21213511591021 has 2 divisors, whose sum is σ = 21213511591022. Its totient is φ = 21213511591020.

The previous prime is 21213511590989. The next prime is 21213511591043. The reversal of 21213511591021 is 12019511531212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12547258768521 + 8666252822500 = 3542211^2 + 2943850^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213511591021 - 2⁵ = 21213511590989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213511591721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606755795510 + 10606755795511.

It is an arithmetic number, because the mean of its divisors is an integer number (10606755795511).

Almost surely, 2^{21213511591021} is an apocalyptic number.

It is an amenable number.

21213511591021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213511591021 is an equidigital number, since it uses as much as digits as its factorization.

21213511591021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5400, while the sum is 34.

The spelling of 21213511591021 in words is "twenty-one trillion, two hundred thirteen billion, five hundred eleven million, five hundred ninety-one thousand, twenty-one".