55720891 has 2 divisors, whose sum is σ = 55720892. Its totient is φ = 55720890.

The previous prime is 55720879. The next prime is 55720921. The reversal of 55720891 is 19802755.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 55720891 - 2¹⁷ = 55589819 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 55720891.

It is not a weakly prime, because it can be changed into another prime (55721891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27860445 + 27860446.

It is an arithmetic number, because the mean of its divisors is an integer number (27860446).

Almost surely, 2^55720891 is an apocalyptic number.

55720891 is a deficient number, since it is larger than the sum of its proper divisors (1).

55720891 is an equidigital number, since it uses as much as digits as its factorization.

55720891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25200, while the sum is 37.

The square root of 55720891 is about 7464.6427242032. The cubic root of 55720891 is about 381.9495629799.

The spelling of 55720891 in words is "fifty-five million, seven hundred twenty thousand, eight hundred ninety-one".