55615621 has 4 divisors (see below), whose sum is σ = 55655200. Its totient is φ = 55576044.

The previous prime is 55615607. The next prime is 55615631. The reversal of 55615621 is 12651655.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 55615621 - 2⁵ = 55615589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55615631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17601 + ... + 20518.

It is an arithmetic number, because the mean of its divisors is an integer number (13913800).

Almost surely, 2^55615621 is an apocalyptic number.

It is an amenable number.

55615621 is a deficient number, since it is larger than the sum of its proper divisors (39579).

55615621 is a wasteful number, since it uses less digits than its factorization.

55615621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39578.

The product of its digits is 9000, while the sum is 31.

The square root of 55615621 is about 7457.5881489929. The cubic root of 55615621 is about 381.7088801941.

The spelling of 55615621 in words is "fifty-five million, six hundred fifteen thousand, six hundred twenty-one".