1561243161 has 16 divisors (see below), whose sum is σ = 2204928000. Its totient is φ = 979239168.

The previous prime is 1561243081. The next prime is 1561243213. The reversal of 1561243161 is 1613421651.

It is a happy number.

It is not a de Polignac number, because 1561243161 - 2¹⁸ = 1560981017 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1561243561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 218280 + ... + 225318.

It is an arithmetic number, because the mean of its divisors is an integer number (137808000).

Almost surely, 2^1561243161 is an apocalyptic number.

It is an amenable number.

1561243161 is a deficient number, since it is larger than the sum of its proper divisors (643684839).

1561243161 is a wasteful number, since it uses less digits than its factorization.

1561243161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11408.

The product of its digits is 4320, while the sum is 30.

The square root of 1561243161 is about 39512.5696582746. The cubic root of 1561243161 is about 1160.0859926837.

The spelling of 1561243161 in words is "one billion, five hundred sixty-one million, two hundred forty-three thousand, one hundred sixty-one".