1561312173 has 4 divisors (see below), whose sum is σ = 2081749568. Its totient is φ = 1040874780.

The previous prime is 1561312169. The next prime is 1561312177. The reversal of 1561312173 is 3712131651.

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 an interprime number because it is at equal distance from previous prime (1561312169) and next prime (1561312177).

It is not a de Polignac number, because 1561312173 - 2² = 1561312169 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561312173.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561312177) 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, 260218693 + ... + 260218698.

It is an arithmetic number, because the mean of its divisors is an integer number (520437392).

Almost surely, 2^1561312173 is an apocalyptic number.

It is an amenable number.

1561312173 is a deficient number, since it is larger than the sum of its proper divisors (520437395).

1561312173 is an equidigital number, since it uses as much as digits as its factorization.

1561312173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520437394.

The product of its digits is 3780, while the sum is 30.

The square root of 1561312173 is about 39513.4429403463. The cubic root of 1561312173 is about 1160.1030856169.

The spelling of 1561312173 in words is "one billion, five hundred sixty-one million, three hundred twelve thousand, one hundred seventy-three".