1561172255 has 4 divisors (see below), whose sum is σ = 1873406712. Its totient is φ = 1248937800.

The previous prime is 1561172209. The next prime is 1561172299. The reversal of 1561172255 is 5522711651.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1561172255 - 2²² = 1556977951 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 156117221 + ... + 156117230.

It is an arithmetic number, because the mean of its divisors is an integer number (468351678).

Almost surely, 2^1561172255 is an apocalyptic number.

1561172255 is a deficient number, since it is larger than the sum of its proper divisors (312234457).

1561172255 is an equidigital number, since it uses as much as digits as its factorization.

1561172255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312234456.

The product of its digits is 21000, while the sum is 35.

The square root of 1561172255 is about 39511.6723893079. The cubic root of 1561172255 is about 1160.0684301189.

The spelling of 1561172255 in words is "one billion, five hundred sixty-one million, one hundred seventy-two thousand, two hundred fifty-five".