1561140861 has 32 divisors (see below), whose sum is σ = 2440458240. Its totient is φ = 869161536.

The previous prime is 1561140851. The next prime is 1561140863. The reversal of 1561140861 is 1680411651.

It is not a de Polignac number, because 1561140861 - 2⁷ = 1561140733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561140863) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 222570 + ... + 229476.

It is an arithmetic number, because the mean of its divisors is an integer number (76264320).

Almost surely, 2^1561140861 is an apocalyptic number.

It is an amenable number.

1561140861 is a deficient number, since it is larger than the sum of its proper divisors (879317379).

1561140861 is a wasteful number, since it uses less digits than its factorization.

1561140861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7193.

The product of its (nonzero) digits is 5760, while the sum is 33.

The square root of 1561140861 is about 39511.2751123018. The cubic root of 1561140861 is about 1160.0606540322.

The spelling of 1561140861 in words is "one billion, five hundred sixty-one million, one hundred forty thousand, eight hundred sixty-one".