1561557672 has 24 divisors (see below), whose sum is σ = 4229218890. Its totient is φ = 520519200.

The previous prime is 1561557671. The next prime is 1561557689. The reversal of 1561557672 is 2767551651.

1561557672 is a `hidden beast` number, since 1 + 5 + 6 + 1 + 5 + 576 + 72 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1219825476 + 341732196 = 34926^2 + 18486^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (1561557671) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10844079 + ... + 10844222.

Almost surely, 2^1561557672 is an apocalyptic number.

1561557672 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1561557672 is an abundant number, since it is smaller than the sum of its proper divisors (2667661218).

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

1561557672 is a wasteful number, since it uses less digits than its factorization.

1561557672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21688313 (or 21688306 counting only the distinct ones).

The product of its digits is 441000, while the sum is 45.

The square root of 1561557672 is about 39516.5493432815. The cubic root of 1561557672 is about 1160.1638868724.

The spelling of 1561557672 in words is "one billion, five hundred sixty-one million, five hundred fifty-seven thousand, six hundred seventy-two".