55721157 has 12 divisors (see below), whose sum is σ = 77667744. Its totient is φ = 35531320.

The previous prime is 55721131. The next prime is 55721161. The reversal of 55721157 is 75112755.

55721157 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 55721157 - 2¹² = 55717061 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55721117) 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 in 11 ways as a sum of consecutive naturals, for example, 15969 + ... + 19142.

It is an arithmetic number, because the mean of its divisors is an integer number (6472312).

Almost surely, 2^55721157 is an apocalyptic number.

It is an amenable number.

55721157 is a deficient number, since it is larger than the sum of its proper divisors (21946587).

55721157 is a wasteful number, since it uses less digits than its factorization.

55721157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35160 (or 35137 counting only the distinct ones).

The product of its digits is 12250, while the sum is 33.

The square root of 55721157 is about 7464.6605415116. The cubic root of 55721157 is about 381.9501707616.

The spelling of 55721157 in words is "fifty-five million, seven hundred twenty-one thousand, one hundred fifty-seven".