1561273755 has 8 divisors (see below), whose sum is σ = 2498038032. Its totient is φ = 832679328.

The previous prime is 1561273751. The next prime is 1561273781. The reversal of 1561273755 is 5573721651.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1561273755 - 2² = 1561273751 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (1561273751) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 52042444 + ... + 52042473.

It is an arithmetic number, because the mean of its divisors is an integer number (312254754).

Almost surely, 2^1561273755 is an apocalyptic number.

1561273755 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1561273755 is a deficient number, since it is larger than the sum of its proper divisors (936764277).

1561273755 is a wasteful number, since it uses less digits than its factorization.

1561273755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104084925.

The product of its digits is 220500, while the sum is 42.

The square root of 1561273755 is about 39512.9567990046. The cubic root of 1561273755 is about 1160.0935702860.

It can be divided in two parts, 1561273 and 755, that added together give a triangular number (1562028 = T₁₇₆₇).

The spelling of 1561273755 in words is "one billion, five hundred sixty-one million, two hundred seventy-three thousand, seven hundred fifty-five".