21655901121 has 8 divisors (see below), whose sum is σ = 28902064800. Its totient is φ = 14423502432.

The previous prime is 21655901117. The next prime is 21655901123. The reversal of 21655901121 is 12110955612.

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

It is not a de Polignac number, because 21655901121 - 2² = 21655901117 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21655901123) 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, 3437575 + ... + 3443868.

It is an arithmetic number, because the mean of its divisors is an integer number (3612758100).

Almost surely, 2^21655901121 is an apocalyptic number.

It is an amenable number.

21655901121 is a deficient number, since it is larger than the sum of its proper divisors (7246163679).

21655901121 is a wasteful number, since it uses less digits than its factorization.

21655901121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6882495.

The product of its (nonzero) digits is 5400, while the sum is 33.

The spelling of 21655901121 in words is "twenty-one billion, six hundred fifty-five million, nine hundred one thousand, one hundred twenty-one".