55872721 has 2 divisors, whose sum is σ = 55872722. Its totient is φ = 55872720.

The previous prime is 55872697. The next prime is 55872779. The reversal of 55872721 is 12727855.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48233025 + 7639696 = 6945^2 + 2764^2 .

It is a cyclic number.

It is not a de Polignac number, because 55872721 - 2²³ = 47484113 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (55872121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27936360 + 27936361.

It is an arithmetic number, because the mean of its divisors is an integer number (27936361).

Almost surely, 2^55872721 is an apocalyptic number.

It is an amenable number.

55872721 is a deficient number, since it is larger than the sum of its proper divisors (1).

55872721 is an equidigital number, since it uses as much as digits as its factorization.

55872721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 39200, while the sum is 37.

The square root of 55872721 is about 7474.8057499844. The cubic root of 55872721 is about 382.2961643380.

The spelling of 55872721 in words is "fifty-five million, eight hundred seventy-two thousand, seven hundred twenty-one".