1555661099 has 2 divisors, whose sum is σ = 1555661100. Its totient is φ = 1555661098.

The previous prime is 1555661089. The next prime is 1555661111. The reversal of 1555661099 is 9901665551.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1555661099 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1555661039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777830549 + 777830550.

It is an arithmetic number, because the mean of its divisors is an integer number (777830550).

Almost surely, 2^1555661099 is an apocalyptic number.

1555661099 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555661099 is an equidigital number, since it uses as much as digits as its factorization.

1555661099 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 364500, while the sum is 47.

The square root of 1555661099 is about 39441.8698720028. The cubic root of 1555661099 is about 1158.7017528332.

The spelling of 1555661099 in words is "one billion, five hundred fifty-five million, six hundred sixty-one thousand, ninety-nine".