21002121899261 has 2 divisors, whose sum is σ = 21002121899262. Its totient is φ = 21002121899260.

The previous prime is 21002121899203. The next prime is 21002121899327. The reversal of 21002121899261 is 16299812120012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20935108740100 + 67013159161 = 4575490^2 + 258869^2 .

It is a cyclic number.

It is not a de Polignac number, because 21002121899261 - 2³⁰ = 21001048157437 is a prime.

It is a super-2 number, since 2×21002121899261² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002121893261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501060949630 + 10501060949631.

It is an arithmetic number, because the mean of its divisors is an integer number (10501060949631).

Almost surely, 2^{21002121899261} is an apocalyptic number.

It is an amenable number.

21002121899261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002121899261 is an equidigital number, since it uses as much as digits as its factorization.

21002121899261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 44.

The spelling of 21002121899261 in words is "twenty-one trillion, two billion, one hundred twenty-one million, eight hundred ninety-nine thousand, two hundred sixty-one".