21455639639 has 8 divisors (see below), whose sum is σ = 24600605568. Its totient is φ = 18330642360.

The previous prime is 21455639573. The next prime is 21455639659. The reversal of 21455639639 is 93693655412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21455639639 - 2²⁸ = 21187204183 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21455639659) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4989857 + ... + 4994154.

It is an arithmetic number, because the mean of its divisors is an integer number (3075075696).

Almost surely, 2^21455639639 is an apocalyptic number.

21455639639 is a deficient number, since it is larger than the sum of its proper divisors (3144965929).

21455639639 is an equidigital number, since it uses as much as digits as its factorization.

21455639639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9984325.

The product of its digits is 5248800, while the sum is 53.

The spelling of 21455639639 in words is "twenty-one billion, four hundred fifty-five million, six hundred thirty-nine thousand, six hundred thirty-nine".