1561904 has 40 divisors (see below), whose sum is σ = 3237888. Its totient is φ = 728640.

The previous prime is 1561891. The next prime is 1561919. The reversal of 1561904 is 4091651.

It is an Ulam number.

It is a nialpdrome in base 11.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23279 + ... + 23345.

2^1561904 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 1561904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1618944).

1561904 is an abundant number, since it is smaller than the sum of its proper divisors (1675984).

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

1561904 is a wasteful number, since it uses less digits than its factorization.

1561904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153 (or 147 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 1561904 is about 1249.7615772618. The cubic root of 1561904 is about 116.0249649003.

The spelling of 1561904 in words is "one million, five hundred sixty-one thousand, nine hundred four".