1609978 has 4 divisors (see below), whose sum is σ = 2414970. Its totient is φ = 804988.

The previous prime is 1609969. The next prime is 1609991. The reversal of 1609978 is 8799061.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8799061 = 2393 ⋅3677.

It can be written as a sum of positive squares in only one way, i.e., 1580049 + 29929 = 1257^2 + 173^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 1609978.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 402493 + ... + 402496.

2^1609978 is an apocalyptic number.

1609978 is a deficient number, since it is larger than the sum of its proper divisors (804992).

1609978 is an equidigital number, since it uses as much as digits as its factorization.

1609978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804991.

The product of its (nonzero) digits is 27216, while the sum is 40.

The square root of 1609978 is about 1268.8490848009. The cubic root of 1609978 is about 117.2033379364.

The spelling of 1609978 in words is "one million, six hundred nine thousand, nine hundred seventy-eight".