55661999 has 2 divisors, whose sum is σ = 55662000. Its totient is φ = 55661998.

The previous prime is 55661993. The next prime is 55662007. The reversal of 55661999 is 99916655.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 55661999 - 2⁸ = 55661743 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55661993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27830999 + 27831000.

It is an arithmetic number, because the mean of its divisors is an integer number (27831000).

Almost surely, 2^55661999 is an apocalyptic number.

55661999 is a deficient number, since it is larger than the sum of its proper divisors (1).

55661999 is an equidigital number, since it uses as much as digits as its factorization.

55661999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 656100, while the sum is 50.

The square root of 55661999 is about 7460.6969513578. The cubic root of 55661999 is about 381.8149533655.

The spelling of 55661999 in words is "fifty-five million, six hundred sixty-one thousand, nine hundred ninety-nine".