21213517590989 has 2 divisors, whose sum is σ = 21213517590990. Its totient is φ = 21213517590988.

The previous prime is 21213517590893. The next prime is 21213517591001. The reversal of 21213517590989 is 98909571531212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17938655514025 + 3274862076964 = 4235405^2 + 1809658^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213517590989 - 2²⁸ = 21213249155533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213517595989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606758795494 + 10606758795495.

It is an arithmetic number, because the mean of its divisors is an integer number (10606758795495).

Almost surely, 2^{21213517590989} is an apocalyptic number.

It is an amenable number.

21213517590989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213517590989 is an equidigital number, since it uses as much as digits as its factorization.

21213517590989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12247200, while the sum is 62.

The spelling of 21213517590989 in words is "twenty-one trillion, two hundred thirteen billion, five hundred seventeen million, five hundred ninety thousand, nine hundred eighty-nine".