1561000591 has 2 divisors, whose sum is σ = 1561000592. Its totient is φ = 1561000590.

The previous prime is 1561000559. The next prime is 1561000627. The reversal of 1561000591 is 1950001651.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1561000591 - 2⁵ = 1561000559 is a prime.

It is the 39510-th Hogben number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561000531) by changing a digit.

It is a nontrivial repunit in base 39509.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780500295 + 780500296.

It is an arithmetic number, because the mean of its divisors is an integer number (780500296).

Almost surely, 2^1561000591 is an apocalyptic number.

1561000591 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561000591 is an equidigital number, since it uses as much as digits as its factorization.

1561000591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1350, while the sum is 28.

The square root of 1561000591 is about 39509.5000094914. The cubic root of 1561000591 is about 1160.0259088050.

The spelling of 1561000591 in words is "one billion, five hundred sixty-one million, five hundred ninety-one", and thus it is an aban number.