1561187775625 has 135 divisors (see below), whose sum is σ = 2130506142457. Its totient is φ = 1143519520000.

The previous prime is 1561187775619. The next prime is 1561187775647. The reversal of 1561187775625 is 5265777811651.

It is a happy number.

The square root of 1561187775625 is 1249475.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 22 ways, for example, as 1035487372921 + 525700402704 = 1017589^2 + 725052^2 .

It is not a de Polignac number, because 1561187775625 - 2²³ = 1561179387017 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 29456373099 + ... + 29456373151.

Almost surely, 2^{1561187775625} is an apocalyptic number.

1561187775625 is the 1249475-th square number.

1561187775625 is the 624738-th centered octagonal number.

It is an amenable number.

1561187775625 is a deficient number, since it is larger than the sum of its proper divisors (569318366832).

1561187775625 is an frugal number, since it uses more digits than its factorization.

1561187775625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254 (or 122 counting only the distinct ones).

The product of its digits is 24696000, while the sum is 61.

The spelling of 1561187775625 in words is "one trillion, five hundred sixty-one billion, one hundred eighty-seven million, seven hundred seventy-five thousand, six hundred twenty-five".