1561457161 has 16 divisors (see below), whose sum is σ = 1747178496. Its totient is φ = 1383120000.

The previous prime is 1561457141. The next prime is 1561457167. The reversal of 1561457161 is 1617541651.

It is a cyclic number.

It is not a de Polignac number, because 1561457161 - 2⁵ = 1561457129 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561457161.

It is not an unprimeable number, because it can be changed into a prime (1561457167) 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, 458776 + ... + 462166.

It is an arithmetic number, because the mean of its divisors is an integer number (109198656).

Almost surely, 2^1561457161 is an apocalyptic number.

1561457161 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1561457161 is a deficient number, since it is larger than the sum of its proper divisors (185721335).

1561457161 is a wasteful number, since it uses less digits than its factorization.

1561457161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4464.

The product of its digits is 25200, while the sum is 37.

The square root of 1561457161 is about 39515.2775645066. The cubic root of 1561457161 is about 1160.1389946902.

It can be divided in two parts, 156145 and 7161, that added together give a triangular number (163306 = T₅₇₁).

The spelling of 1561457161 in words is "one billion, five hundred sixty-one million, four hundred fifty-seven thousand, one hundred sixty-one".