1978649 has 8 divisors (see below), whose sum is σ = 2072520. Its totient is φ = 1886976.

The previous prime is 1978631. The next prime is 1978661. The reversal of 1978649 is 9468791.

It can be written as a sum of positive squares in 4 ways, for example, as 697225 + 1281424 = 835^2 + 1132^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1978649 - 2⁸ = 1978393 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1978349) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1457 + ... + 2465.

It is an arithmetic number, because the mean of its divisors is an integer number (259065).

2^1978649 is an apocalyptic number.

It is an amenable number.

1978649 is a deficient number, since it is larger than the sum of its proper divisors (93871).

1978649 is a wasteful number, since it uses less digits than its factorization.

1978649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1099.

The product of its digits is 108864, while the sum is 44.

The square root of 1978649 is about 1406.6445890843. The cubic root of 1978649 is about 125.5421571256.

The spelling of 1978649 in words is "one million, nine hundred seventy-eight thousand, six hundred forty-nine".