1561025988 has 18 divisors (see below), whose sum is σ = 3945926894. Its totient is φ = 520341984.

The previous prime is 1561025971. The next prime is 1561026011. The reversal of 1561025988 is 8895201651.

It is a happy number.

1561025988 is a `hidden beast` number, since 1 + 5 + 610 + 25 + 9 + 8 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1231167744 + 329858244 = 35088^2 + 18162^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×1561025988² = 4873604270422752288, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 21680881 + ... + 21680952.

Almost surely, 2^1561025988 is an apocalyptic number.

1561025988 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1561025988 is an abundant number, since it is smaller than the sum of its proper divisors (2384900906).

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

1561025988 is a wasteful number, since it uses less digits than its factorization.

1561025988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43361843 (or 43361838 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 45.

The square root of 1561025988 is about 39509.8214118971. The cubic root of 1561025988 is about 1160.0321998592.

The spelling of 1561025988 in words is "one billion, five hundred sixty-one million, twenty-five thousand, nine hundred eighty-eight".