21639712618639 has 2 divisors, whose sum is σ = 21639712618640. Its totient is φ = 21639712618638.

The previous prime is 21639712618631. The next prime is 21639712618649. The reversal of 21639712618639 is 93681621793612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21639712618639 - 2³ = 21639712618631 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21639712618631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10819856309319 + 10819856309320.

It is an arithmetic number, because the mean of its divisors is an integer number (10819856309320).

Almost surely, 2^{21639712618639} is an apocalyptic number.

21639712618639 is a deficient number, since it is larger than the sum of its proper divisors (1).

21639712618639 is an equidigital number, since it uses as much as digits as its factorization.

21639712618639 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 35271936, while the sum is 64.

The spelling of 21639712618639 in words is "twenty-one trillion, six hundred thirty-nine billion, seven hundred twelve million, six hundred eighteen thousand, six hundred thirty-nine".