1561321256 has 32 divisors (see below), whose sum is σ = 3303741600. Its totient is φ = 685218240.

The previous prime is 1561321249. The next prime is 1561321261. The reversal of 1561321256 is 6521231651.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 303350 + ... + 308453.

It is an arithmetic number, because the mean of its divisors is an integer number (103241925).

Almost surely, 2^1561321256 is an apocalyptic number.

It is an amenable number.

1561321256 is an abundant number, since it is smaller than the sum of its proper divisors (1742420344).

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

1561321256 is a wasteful number, since it uses less digits than its factorization.

1561321256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 611849 (or 611845 counting only the distinct ones).

The product of its digits is 10800, while the sum is 32.

The square root of 1561321256 is about 39513.5578757469. The cubic root of 1561321256 is about 1160.1053352622.

The spelling of 1561321256 in words is "one billion, five hundred sixty-one million, three hundred twenty-one thousand, two hundred fifty-six".