55617221 has 8 divisors (see below), whose sum is σ = 61405344. Its totient is φ = 49951120.

The previous prime is 55617187. The next prime is 55617227. The reversal of 55617221 is 12271655.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55617221 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55617227) 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, 29546 + ... + 31371.

It is an arithmetic number, because the mean of its divisors is an integer number (7675668).

Almost surely, 2^55617221 is an apocalyptic number.

It is an amenable number.

55617221 is a deficient number, since it is larger than the sum of its proper divisors (5788123).

55617221 is a wasteful number, since it uses less digits than its factorization.

55617221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61011.

The product of its digits is 4200, while the sum is 29.

The square root of 55617221 is about 7457.6954215092. The cubic root of 55617221 is about 381.7125406066.

Adding to 55617221 its reverse (12271655), we get a palindrome (67888876).

The spelling of 55617221 in words is "fifty-five million, six hundred seventeen thousand, two hundred twenty-one".