1978638 has 8 divisors (see below), whose sum is σ = 3957288. Its totient is φ = 659544.

The previous prime is 1978631. The next prime is 1978661. The reversal of 1978638 is 8368791.

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

1978638 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 1978638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978631) 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, 164881 + ... + 164892.

It is an arithmetic number, because the mean of its divisors is an integer number (494661).

2^1978638 is an apocalyptic number.

1978638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

1978638 is a wasteful number, since it uses less digits than its factorization.

1978638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329778.

The product of its digits is 72576, while the sum is 42.

The square root of 1978638 is about 1406.6406790648. The cubic root of 1978638 is about 125.5419244809.

The spelling of 1978638 in words is "one million, nine hundred seventy-eight thousand, six hundred thirty-eight".