1561251380 has 24 divisors (see below), whose sum is σ = 3530830632. Its totient is φ = 576461952.

The previous prime is 1561251361. The next prime is 1561251401. The reversal of 1561251380 is 831521651.

It can be written as a sum of positive squares in 4 ways, for example, as 2896804 + 1558354576 = 1702^2 + 39476^2 .

It is a congruent number.

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, 3002147 + ... + 3002666.

It is an arithmetic number, because the mean of its divisors is an integer number (147117943).

Almost surely, 2^1561251380 is an apocalyptic number.

1561251380 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561251380 is an abundant number, since it is smaller than the sum of its proper divisors (1969579252).

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

1561251380 is a wasteful number, since it uses less digits than its factorization.

1561251380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6004835 (or 6004833 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 1561251380 is about 39512.6736630160. The cubic root of 1561251380 is about 1160.0880283969.

The spelling of 1561251380 in words is "one billion, five hundred sixty-one million, two hundred fifty-one thousand, three hundred eighty".