55917021 has 8 divisors (see below), whose sum is σ = 74594880. Its totient is φ = 37258592.

The previous prime is 55917013. The next prime is 55917031. The reversal of 55917021 is 12071955.

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

It is a cyclic number.

It is not a de Polignac number, because 55917021 - 2³ = 55917013 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 55917021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55917031) 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, 4360 + ... + 11438.

It is an arithmetic number, because the mean of its divisors is an integer number (9324360).

Almost surely, 2^55917021 is an apocalyptic number.

It is an amenable number.

55917021 is a deficient number, since it is larger than the sum of its proper divisors (18677859).

55917021 is a wasteful number, since it uses less digits than its factorization.

55917021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9715.

The product of its (nonzero) digits is 3150, while the sum is 30.

The square root of 55917021 is about 7477.7684505473. The cubic root of 55917021 is about 382.3971751460.

Adding to 55917021 its reverse (12071955), we get a palindrome (67988976).

The spelling of 55917021 in words is "fifty-five million, nine hundred seventeen thousand, twenty-one".