21244216121 has 2 divisors, whose sum is σ = 21244216122. Its totient is φ = 21244216120.

The previous prime is 21244216099. The next prime is 21244216181. The reversal of 21244216121 is 12161244212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18256063225 + 2988152896 = 135115^2 + 54664^2 .

It is a cyclic number.

It is not a de Polignac number, because 21244216121 - 2³⁰ = 20170474297 is a prime.

It is not a weakly prime, because it can be changed into another prime (21244216181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10622108060 + 10622108061.

It is an arithmetic number, because the mean of its divisors is an integer number (10622108061).

Almost surely, 2^21244216121 is an apocalyptic number.

It is an amenable number.

21244216121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21244216121 is an equidigital number, since it uses as much as digits as its factorization.

21244216121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1536, while the sum is 26.

The spelling of 21244216121 in words is "twenty-one billion, two hundred forty-four million, two hundred sixteen thousand, one hundred twenty-one".