1561841640 has 48 divisors (see below), whose sum is σ = 5075986500. Its totient is φ = 416491008.

The previous prime is 1561841587. The next prime is 1561841641. The reversal of 1561841640 is 461481651.

1561841640 is a `hidden beast` number, since 1 + 5 + 6 + 1 + 8 + 4 + 1 + 640 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1492585956 + 69255684 = 38634^2 + 8322^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1561841595 and 1561841604.

It is not an unprimeable number, because it can be changed into a prime (1561841641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2168865 + ... + 2169584.

Almost surely, 2^1561841640 is an apocalyptic number.

1561841640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561841640 is an abundant number, since it is smaller than the sum of its proper divisors (3514144860).

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

1561841640 is a wasteful number, since it uses less digits than its factorization.

1561841640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4338466 (or 4338459 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 1561841640 is about 39520.1422062219. The cubic root of 1561841640 is about 1160.2342075649.

The spelling of 1561841640 in words is "one billion, five hundred sixty-one million, eight hundred forty-one thousand, six hundred forty".