561271956 has 96 divisors (see below), whose sum is σ = 1537536000. Its totient is φ = 156048768.

The previous prime is 561271939. The next prime is 561271987. The reversal of 561271956 is 659172165.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 539685 + ... + 540723.

It is an arithmetic number, because the mean of its divisors is an integer number (16016000).

Almost surely, 2^561271956 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 561271956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (768768000).

561271956 is an abundant number, since it is smaller than the sum of its proper divisors (976264044).

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

561271956 is a wasteful number, since it uses less digits than its factorization.

561271956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1221 (or 1219 counting only the distinct ones).

The product of its digits is 113400, while the sum is 42.

The square root of 561271956 is about 23691.1788647167. The cubic root of 561271956 is about 824.8806468294.

The spelling of 561271956 in words is "five hundred sixty-one million, two hundred seventy-one thousand, nine hundred fifty-six".