21506633390639 has 2 divisors, whose sum is σ = 21506633390640. Its totient is φ = 21506633390638.

The previous prime is 21506633390497. The next prime is 21506633390681. The reversal of 21506633390639 is 93609333660512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21506633390639 - 2⁸ = 21506633390383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21506633390699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753316695319 + 10753316695320.

It is an arithmetic number, because the mean of its divisors is an integer number (10753316695320).

Almost surely, 2^{21506633390639} is an apocalyptic number.

21506633390639 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506633390639 is an equidigital number, since it uses as much as digits as its factorization.

21506633390639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14171760, while the sum is 56.

The spelling of 21506633390639 in words is "twenty-one trillion, five hundred six billion, six hundred thirty-three million, three hundred ninety thousand, six hundred thirty-nine".