55661591 has 2 divisors, whose sum is σ = 55661592. Its totient is φ = 55661590.

The previous prime is 55661581. The next prime is 55661597. The reversal of 55661591 is 19516655.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 55661591 - 2¹⁴ = 55645207 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55661597) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27830795 + 27830796.

It is an arithmetic number, because the mean of its divisors is an integer number (27830796).

Almost surely, 2^55661591 is an apocalyptic number.

55661591 is a deficient number, since it is larger than the sum of its proper divisors (1).

55661591 is an equidigital number, since it uses as much as digits as its factorization.

55661591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40500, while the sum is 38.

The square root of 55661591 is about 7460.6696080178. The cubic root of 55661591 is about 381.8140204676.

The spelling of 55661591 in words is "fifty-five million, six hundred sixty-one thousand, five hundred ninety-one".