1561687680 has 256 divisors, whose sum is σ = 5738895360. Its totient is φ = 353832960.

The previous prime is 1561687679. The next prime is 1561687739. The reversal of 1561687680 is 867861651.

It is a Harshad number since it is a multiple of its sum of digits (48).

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, 1760197 + ... + 1761083.

It is an arithmetic number, because the mean of its divisors is an integer number (22417560).

Almost surely, 2^1561687680 is an apocalyptic number.

1561687680 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 1561687680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2869447680).

1561687680 is an abundant number, since it is smaller than the sum of its proper divisors (4177207680).

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

1561687680 is a wasteful number, since it uses less digits than its factorization.

1561687680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1047 (or 1035 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 48.

The square root of 1561687680 is about 39518.1942907315. The cubic root of 1561687680 is about 1160.1960825882.

The spelling of 1561687680 in words is "one billion, five hundred sixty-one million, six hundred eighty-seven thousand, six hundred eighty".