1561403844 has 432 divisors, whose sum is σ = 5560974720. Its totient is φ = 370656000.

The previous prime is 1561403843. The next prime is 1561403863. The reversal of 1561403844 is 4483041651.

1561403844 is a `hidden beast` number, since 1 + 5 + 614 + 0 + 38 + 4 + 4 = 666.

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 = 1561403799 and 1561403808.

It is not an unprimeable number, because it can be changed into a prime (1561403843) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 15459394 + ... + 15459494.

Almost surely, 2^1561403844 is an apocalyptic number.

1561403844 is a gapful number since it is divisible by the number (14) 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 1561403844, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2780487360).

1561403844 is an abundant number, since it is smaller than the sum of its proper divisors (3999570876).

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

1561403844 is a wasteful number, since it uses less digits than its factorization.

1561403844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 1561403844 is about 39514.6029209456. The cubic root of 1561403844 is about 1160.1257899657.

The spelling of 1561403844 in words is "one billion, five hundred sixty-one million, four hundred three thousand, eight hundred forty-four".