1561165755 has 16 divisors (see below), whose sum is σ = 2499807744. Its totient is φ = 831974240.

The previous prime is 1561165751. The next prime is 1561165849. The reversal of 1561165755 is 5575611651.

It is not a de Polignac number, because 1561165755 - 2² = 1561165751 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1561165751) 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, 20211 + ... + 59420.

It is an arithmetic number, because the mean of its divisors is an integer number (156237984).

Almost surely, 2^1561165755 is an apocalyptic number.

1561165755 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1561165755 is a deficient number, since it is larger than the sum of its proper divisors (938641989).

1561165755 is a wasteful number, since it uses less digits than its factorization.

1561165755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80946.

The product of its digits is 157500, while the sum is 42.

The square root of 1561165755 is about 39511.5901350477. The cubic root of 1561165755 is about 1160.0668201203.

The spelling of 1561165755 in words is "one billion, five hundred sixty-one million, one hundred sixty-five thousand, seven hundred fifty-five".