21798947903021 has 2 divisors, whose sum is σ = 21798947903022. Its totient is φ = 21798947903020.

The previous prime is 21798947902999. The next prime is 21798947903041. The reversal of 21798947903021 is 12030974989712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20444550049225 + 1354397853796 = 4521565^2 + 1163786^2 .

It is a cyclic number.

It is not a de Polignac number, because 21798947903021 - 2²⁶ = 21798880794157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21798947903041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10899473951510 + 10899473951511.

It is an arithmetic number, because the mean of its divisors is an integer number (10899473951511).

Almost surely, 2^{21798947903021} is an apocalyptic number.

It is an amenable number.

21798947903021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21798947903021 is an equidigital number, since it uses as much as digits as its factorization.

21798947903021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13716864, while the sum is 62.

The spelling of 21798947903021 in words is "twenty-one trillion, seven hundred ninety-eight billion, nine hundred forty-seven million, nine hundred three thousand, twenty-one".