1978685 has 4 divisors (see below), whose sum is σ = 2374428. Its totient is φ = 1582944.

The previous prime is 1978673. The next prime is 1978687. The reversal of 1978685 is 5868791.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 770884 + 1207801 = 878^2 + 1099^2 .

It is a cyclic number.

It is not a de Polignac number, because 1978685 - 2⁸ = 1978429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 197864 + ... + 197873.

It is an arithmetic number, because the mean of its divisors is an integer number (593607).

2^1978685 is an apocalyptic number.

It is an amenable number.

1978685 is a deficient number, since it is larger than the sum of its proper divisors (395743).

1978685 is an equidigital number, since it uses as much as digits as its factorization.

1978685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 395742.

The product of its digits is 120960, while the sum is 44.

The square root of 1978685 is about 1406.6573854354. The cubic root of 1978685 is about 125.5429185020.

The spelling of 1978685 in words is "one million, nine hundred seventy-eight thousand, six hundred eighty-five".