21661418055 has 32 divisors (see below), whose sum is σ = 36283129344. Its totient is φ = 11014413696.

The previous prime is 21661418041. The next prime is 21661418063. The reversal of 21661418055 is 55081416612.

It is not a de Polignac number, because 21661418055 - 2²⁵ = 21627863623 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3657 + ... + 208173.

It is an arithmetic number, because the mean of its divisors is an integer number (1133847792).

Almost surely, 2^21661418055 is an apocalyptic number.

21661418055 is a deficient number, since it is larger than the sum of its proper divisors (14621711289).

21661418055 is a wasteful number, since it uses less digits than its factorization.

21661418055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204855.

The product of its (nonzero) digits is 57600, while the sum is 39.

The spelling of 21661418055 in words is "twenty-one billion, six hundred sixty-one million, four hundred eighteen thousand, fifty-five".