1561681408 has 160 divisors (see below), whose sum is σ = 3720904704. Its totient is φ = 640991232.

The previous prime is 1561681399. The next prime is 1561681417. The reversal of 1561681408 is 8041861651.

It is an interprime number because it is at equal distance from previous prime (1561681399) and next prime (1561681417).

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12296641 + ... + 12296767.

Almost surely, 2^1561681408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1561681408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1860452352).

1561681408 is an abundant number, since it is smaller than the sum of its proper divisors (2159223296).

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

1561681408 is an equidigital number, since it uses as much as digits as its factorization.

1561681408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272 (or 256 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 40.

The square root of 1561681408 is about 39518.1149347992. The cubic root of 1561681408 is about 1160.1945294054.

The spelling of 1561681408 in words is "one billion, five hundred sixty-one million, six hundred eighty-one thousand, four hundred eight".