1561864680 has 160 divisors (see below), whose sum is σ = 5478105600. Its totient is φ = 398369664.

The previous prime is 1561864663. The next prime is 1561864691. The reversal of 1561864680 is 864681651.

1561864680 is a `hidden beast` number, since 1 + 5 + 6 + 186 + 468 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 64041 + ... + 84999.

It is an arithmetic number, because the mean of its divisors is an integer number (34238160).

Almost surely, 2^1561864680 is an apocalyptic number.

1561864680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1561864680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2739052800).

1561864680 is an abundant number, since it is smaller than the sum of its proper divisors (3916240920).

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

1561864680 is a wasteful number, since it uses less digits than its factorization.

1561864680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21005 (or 20992 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The square root of 1561864680 is about 39520.4337020737. The cubic root of 1561864680 is about 1160.2399127239.

The spelling of 1561864680 in words is "one billion, five hundred sixty-one million, eight hundred sixty-four thousand, six hundred eighty".