55721881 has 2 divisors, whose sum is σ = 55721882. Its totient is φ = 55721880.

The previous prime is 55721879. The next prime is 55721891. The reversal of 55721881 is 18812755.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 54243225 + 1478656 = 7365^2 + 1216^2 .

It is a cyclic number.

It is not a de Polignac number, because 55721881 - 2¹ = 55721879 is a prime.

It is a super-2 number, since 2×55721881² = 6209856044356322, which contains 22 as substring.

Together with 55721879, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 55721881.

It is not a weakly prime, because it can be changed into another prime (55721821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27860940 + 27860941.

It is an arithmetic number, because the mean of its divisors is an integer number (27860941).

Almost surely, 2^55721881 is an apocalyptic number.

It is an amenable number.

55721881 is a deficient number, since it is larger than the sum of its proper divisors (1).

55721881 is an equidigital number, since it uses as much as digits as its factorization.

55721881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22400, while the sum is 37.

The square root of 55721881 is about 7464.7090365265. The cubic root of 55721881 is about 381.9518250149.

The spelling of 55721881 in words is "fifty-five million, seven hundred twenty-one thousand, eight hundred eighty-one".