199555561 has 16 divisors (see below), whose sum is σ = 209873664. Its totient is φ = 189552384.

The previous prime is 199555553. The next prime is 199555591. The reversal of 199555561 is 165555991.

199555561 = 266² + 267² + ... + 851².

It is a cyclic number.

It is not a de Polignac number, because 199555561 - 2³ = 199555553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199555591) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 591985 + ... + 592321.

It is an arithmetic number, because the mean of its divisors is an integer number (13117104).

Almost surely, 2^199555561 is an apocalyptic number.

It is an amenable number.

199555561 is a deficient number, since it is larger than the sum of its proper divisors (10318103).

199555561 is a wasteful number, since it uses less digits than its factorization.

199555561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 720.

The product of its digits is 303750, while the sum is 46.

The square root of 199555561 is about 14126.4135929825. The cubic root of 199555561 is about 584.3700438673.

The spelling of 199555561 in words is "one hundred ninety-nine million, five hundred fifty-five thousand, five hundred sixty-one".