1561491959 has 6 divisors (see below), whose sum is σ = 1581514200. Its totient is φ = 1541720076.

The previous prime is 1561491937. The next prime is 1561491977. The reversal of 1561491959 is 9591941651.

It is not a de Polignac number, because 1561491959 - 2⁸ = 1561491703 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561491559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 118859 + ... + 131340.

It is an arithmetic number, because the mean of its divisors is an integer number (263585700).

Almost surely, 2^1561491959 is an apocalyptic number.

1561491959 is a deficient number, since it is larger than the sum of its proper divisors (20022241).

1561491959 is an frugal number, since it uses more digits than its factorization.

1561491959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250357 (or 250278 counting only the distinct ones).

The product of its digits is 437400, while the sum is 50.

The square root of 1561491959 is about 39515.7178727655. The cubic root of 1561491959 is about 1160.1476127550.

The spelling of 1561491959 in words is "one billion, five hundred sixty-one million, four hundred ninety-one thousand, nine hundred fifty-nine".