21615554546651 has 16 divisors (see below), whose sum is σ = 23524971468768. Its totient is φ = 19741650240000.

The previous prime is 21615554546617. The next prime is 21615554546653. The reversal of 21615554546651 is 15664545551612.

It is not a de Polignac number, because 21615554546651 - 2¹⁸ = 21615554284507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21615554546653) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3767726 + ... + 7578051.

It is an arithmetic number, because the mean of its divisors is an integer number (1470310716798).

Almost surely, 2^{21615554546651} is an apocalyptic number.

21615554546651 is a deficient number, since it is larger than the sum of its proper divisors (1909416922117).

21615554546651 is a wasteful number, since it uses less digits than its factorization.

21615554546651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11347342.

The product of its digits is 21600000, while the sum is 56.

The spelling of 21615554546651 in words is "twenty-one trillion, six hundred fifteen billion, five hundred fifty-four million, five hundred forty-six thousand, six hundred fifty-one".