1561725913 has 4 divisors (see below), whose sum is σ = 1703701008. Its totient is φ = 1419750820.

The previous prime is 1561725911. The next prime is 1561725923. The reversal of 1561725913 is 3195271651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1561725913 - 2¹ = 1561725911 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561725911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70987531 + ... + 70987552.

It is an arithmetic number, because the mean of its divisors is an integer number (425925252).

Almost surely, 2^1561725913 is an apocalyptic number.

It is an amenable number.

1561725913 is a deficient number, since it is larger than the sum of its proper divisors (141975095).

1561725913 is a wasteful number, since it uses less digits than its factorization.

1561725913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141975094.

The product of its digits is 56700, while the sum is 40.

The square root of 1561725913 is about 39518.6780269786. The cubic root of 1561725913 is about 1160.2055504256.

The spelling of 1561725913 in words is "one billion, five hundred sixty-one million, seven hundred twenty-five thousand, nine hundred thirteen".