1561775725 has 24 divisors (see below), whose sum is σ = 1993309920. Its totient is φ = 1213350720.

The previous prime is 1561775707. The next prime is 1561775729. The reversal of 1561775725 is 5275771651.

It is not a de Polignac number, because 1561775725 - 2¹⁵ = 1561742957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561775729) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 116047 + ... + 128803.

It is an arithmetic number, because the mean of its divisors is an integer number (83054580).

Almost surely, 2^1561775725 is an apocalyptic number.

It is an amenable number.

1561775725 is a deficient number, since it is larger than the sum of its proper divisors (431534195).

1561775725 is a wasteful number, since it uses less digits than its factorization.

1561775725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12909 (or 12904 counting only the distinct ones).

The product of its digits is 514500, while the sum is 46.

The square root of 1561775725 is about 39519.3082555856. The cubic root of 1561775725 is about 1160.2178853993.

It can be divided in two parts, 1561775 and 725, that added together give a square (1562500 = 1250²).

The spelling of 1561775725 in words is "one billion, five hundred sixty-one million, seven hundred seventy-five thousand, seven hundred twenty-five".