1561139 has 2 divisors, whose sum is σ = 1561140. Its totient is φ = 1561138.

The previous prime is 1561123. The next prime is 1561151. The reversal of 1561139 is 9311651.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1561139 - 2⁴ = 1561123 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1561159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780569 + 780570.

It is an arithmetic number, because the mean of its divisors is an integer number (780570).

2^1561139 is an apocalyptic number.

1561139 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561139 is an equidigital number, since it uses as much as digits as its factorization.

1561139 is an evil number, because the sum of its binary digits is even.

The product of its digits is 810, while the sum is 26.

The square root of 1561139 is about 1249.4554813998. The cubic root of 1561139 is about 116.0060193071.

The spelling of 1561139 in words is "one million, five hundred sixty-one thousand, one hundred thirty-nine".