20421522464509 has 2 divisors, whose sum is σ = 20421522464510. Its totient is φ = 20421522464508.

The previous prime is 20421522464503. The next prime is 20421522464579. The reversal of 20421522464509 is 90546422512402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11639765124100 + 8781757340409 = 3411710^2 + 2963403^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421522464509 - 2¹⁵ = 20421522431741 is a prime.

It is a super-2 number, since 2×20421522464509² (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 (20421522464503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210761232254 + 10210761232255.

It is an arithmetic number, because the mean of its divisors is an integer number (10210761232255).

Almost surely, 2^{20421522464509} is an apocalyptic number.

It is an amenable number.

20421522464509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421522464509 is an equidigital number, since it uses as much as digits as its factorization.

20421522464509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1382400, while the sum is 46.

The spelling of 20421522464509 in words is "twenty trillion, four hundred twenty-one billion, five hundred twenty-two million, four hundred sixty-four thousand, five hundred nine".