55157821 has 2 divisors, whose sum is σ = 55157822. Its totient is φ = 55157820.

The previous prime is 55157813. The next prime is 55157849. The reversal of 55157821 is 12875155.

55157821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 52562500 + 2595321 = 7250^2 + 1611^2 .

It is a cyclic number.

It is not a de Polignac number, because 55157821 - 2³ = 55157813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55157881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27578910 + 27578911.

It is an arithmetic number, because the mean of its divisors is an integer number (27578911).

Almost surely, 2^55157821 is an apocalyptic number.

It is an amenable number.

55157821 is a deficient number, since it is larger than the sum of its proper divisors (1).

55157821 is an equidigital number, since it uses as much as digits as its factorization.

55157821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14000, while the sum is 34.

The square root of 55157821 is about 7426.8311546716. The cubic root of 55157821 is about 380.6586476528.

The spelling of 55157821 in words is "fifty-five million, one hundred fifty-seven thousand, eight hundred twenty-one".