55491781 has 2 divisors, whose sum is σ = 55491782. Its totient is φ = 55491780.

The previous prime is 55491773. The next prime is 55491811. The reversal of 55491781 is 18719455.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 54626881 + 864900 = 7391^2 + 930^2 .

It is a cyclic number.

It is not a de Polignac number, because 55491781 - 2³ = 55491773 is a prime.

It is a super-2 number, since 2×55491781² = 6158675517103922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55492781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27745890 + 27745891.

It is an arithmetic number, because the mean of its divisors is an integer number (27745891).

Almost surely, 2^55491781 is an apocalyptic number.

It is an amenable number.

55491781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55491781 is an equidigital number, since it uses as much as digits as its factorization.

55491781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 50400, while the sum is 40.

The square root of 55491781 is about 7449.2805692899. The cubic root of 55491781 is about 381.4253509954.

The spelling of 55491781 in words is "fifty-five million, four hundred ninety-one thousand, seven hundred eighty-one".