21515630639 has 8 divisors (see below), whose sum is σ = 22043715792. Its totient is φ = 20987703360.

The previous prime is 21515630519. The next prime is 21515630659. The reversal of 21515630639 is 93603651512.

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 21515630639 - 2²⁴ = 21498853423 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21515630596 and 21515630605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21515630659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 264872 + ... + 336434.

It is an arithmetic number, because the mean of its divisors is an integer number (2755464474).

Almost surely, 2^21515630639 is an apocalyptic number.

21515630639 is a deficient number, since it is larger than the sum of its proper divisors (528085153).

21515630639 is an equidigital number, since it uses as much as digits as its factorization.

21515630639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78937.

The product of its (nonzero) digits is 145800, while the sum is 41.

The spelling of 21515630639 in words is "twenty-one billion, five hundred fifteen million, six hundred thirty thousand, six hundred thirty-nine".