1561978 has 8 divisors (see below), whose sum is σ = 2556000. Its totient is φ = 709980.

The previous prime is 1561919. The next prime is 1562051. The reversal of 1561978 is 8791651.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35478 + ... + 35521.

It is an arithmetic number, because the mean of its divisors is an integer number (319500).

2^1561978 is an apocalyptic number.

1561978 is a deficient number, since it is larger than the sum of its proper divisors (994022).

1561978 is a wasteful number, since it uses less digits than its factorization.

1561978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71012.

The product of its digits is 15120, while the sum is 37.

The square root of 1561978 is about 1249.7911825581. The cubic root of 1561978 is about 116.0267972177.

The spelling of 1561978 in words is "one million, five hundred sixty-one thousand, nine hundred seventy-eight".