1561981575 has 72 divisors (see below), whose sum is σ = 3277290240. Its totient is φ = 649118400.

The previous prime is 1561981559. The next prime is 1561981637. The reversal of 1561981575 is 5751891651.

It is not a de Polignac number, because 1561981575 - 2⁴ = 1561981559 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 21106 + ... + 59744.

It is an arithmetic number, because the mean of its divisors is an integer number (45517920).

Almost surely, 2^1561981575 is an apocalyptic number.

1561981575 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1561981575 is an abundant number, since it is smaller than the sum of its proper divisors (1715308665).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1561981575 is a wasteful number, since it uses less digits than its factorization.

1561981575 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38677 (or 38665 counting only the distinct ones).

The product of its digits is 378000, while the sum is 48.

The square root of 1561981575 is about 39521.9125928895. The cubic root of 1561981575 is about 1160.2688573700.

The spelling of 1561981575 in words is "one billion, five hundred sixty-one million, nine hundred eighty-one thousand, five hundred seventy-five".