1561720125 has 64 divisors (see below), whose sum is σ = 3099193344. Its totient is φ = 682862400.

The previous prime is 1561720123. The next prime is 1561720141. The reversal of 1561720125 is 5210271651.

It is not a de Polignac number, because 1561720125 - 2¹ = 1561720123 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1561720092 and 1561720101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561720123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 47442 + ... + 73308.

It is an arithmetic number, because the mean of its divisors is an integer number (48424896).

Almost surely, 2^1561720125 is an apocalyptic number.

1561720125 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1561720125 is a deficient number, since it is larger than the sum of its proper divisors (1537473219).

1561720125 is a wasteful number, since it uses less digits than its factorization.

1561720125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25915 (or 25905 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 30.

The square root of 1561720125 is about 39518.6047957162. The cubic root of 1561720125 is about 1160.2041171228.

Adding to 1561720125 its reverse (5210271651), we get a palindrome (6771991776).

The spelling of 1561720125 in words is "one billion, five hundred sixty-one million, seven hundred twenty thousand, one hundred twenty-five".