1561409178 has 64 divisors (see below), whose sum is σ = 3692716032. Its totient is φ = 430712640.

The previous prime is 1561409153. The next prime is 1561409219. The reversal of 1561409178 is 8719041651.

It is a super-2 number, since 2×1561409178² = 4875997242285271368, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (42).

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, 679800 + ... + 682092.

It is an arithmetic number, because the mean of its divisors is an integer number (57698688).

Almost surely, 2^1561409178 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1561409178, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1846358016).

1561409178 is an abundant number, since it is smaller than the sum of its proper divisors (2131306854).

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

1561409178 is a wasteful number, since it uses less digits than its factorization.

1561409178 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2859.

The product of its (nonzero) digits is 60480, while the sum is 42.

The square root of 1561409178 is about 39514.6704149231. The cubic root of 1561409178 is about 1160.1271110213.

The spelling of 1561409178 in words is "one billion, five hundred sixty-one million, four hundred nine thousand, one hundred seventy-eight".