55661767220421 has 12 divisors (see below), whose sum is σ = 80464702207500. Its totient is φ = 37078134762240.

The previous prime is 55661767220419. The next prime is 55661767220441. The reversal of 55661767220421 is 12402276716655.

55661767220421 is a `hidden beast` number, since 5 + 5 + 6 + 61 + 76 + 72 + 20 + 421 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 43919912384100 + 11741854836321 = 6627210^2 + 3426639^2 .

It is not a de Polignac number, because 55661767220421 - 2¹ = 55661767220419 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55661767220441) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2475825750 + ... + 2475848231.

It is an arithmetic number, because the mean of its divisors is an integer number (6705391850625).

Almost surely, 2^{55661767220421} is an apocalyptic number.

It is an amenable number.

55661767220421 is a deficient number, since it is larger than the sum of its proper divisors (24802934987079).

55661767220421 is a wasteful number, since it uses less digits than its factorization.

55661767220421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4951675236 (or 4951675233 counting only the distinct ones).

The product of its (nonzero) digits is 8467200, while the sum is 54.

The spelling of 55661767220421 in words is "fifty-five trillion, six hundred sixty-one billion, seven hundred sixty-seven million, two hundred twenty thousand, four hundred twenty-one".