1561242755 has 4 divisors (see below), whose sum is σ = 1873491312. Its totient is φ = 1248994200.

The previous prime is 1561242733. The next prime is 1561242769. The reversal of 1561242755 is 5572421651.

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

It is not a de Polignac number, because 1561242755 - 2⁸ = 1561242499 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 156124271 + ... + 156124280.

It is an arithmetic number, because the mean of its divisors is an integer number (468372828).

Almost surely, 2^1561242755 is an apocalyptic number.

1561242755 is a deficient number, since it is larger than the sum of its proper divisors (312248557).

1561242755 is an equidigital number, since it uses as much as digits as its factorization.

1561242755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312248556.

The product of its digits is 84000, while the sum is 38.

The square root of 1561242755 is about 39512.5645206686. The cubic root of 1561242755 is about 1160.0858921239.

The spelling of 1561242755 in words is "one billion, five hundred sixty-one million, two hundred forty-two thousand, seven hundred fifty-five".