55321921 has 4 divisors (see below), whose sum is σ = 55387332. Its totient is φ = 55256512.

The previous prime is 55321909. The next prime is 55321991. The reversal of 55321921 is 12912355.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 22420225 + 32901696 = 4735^2 + 5736^2 .

It is a cyclic number.

It is not a de Polignac number, because 55321921 - 2⁷ = 55321793 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 55321921.

It is not an unprimeable number, because it can be changed into a prime (55321991) 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, 31420 + ... + 33133.

It is an arithmetic number, because the mean of its divisors is an integer number (13846833).

Almost surely, 2^55321921 is an apocalyptic number.

It is an amenable number.

55321921 is a deficient number, since it is larger than the sum of its proper divisors (65411).

55321921 is an equidigital number, since it uses as much as digits as its factorization.

55321921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65410.

The product of its digits is 2700, while the sum is 28.

The square root of 55321921 is about 7437.8707302561. The cubic root of 55321921 is about 381.0357730089.

The spelling of 55321921 in words is "fifty-five million, three hundred twenty-one thousand, nine hundred twenty-one".