1978539 has 4 divisors (see below), whose sum is σ = 2638056. Its totient is φ = 1319024.

The previous prime is 1978531. The next prime is 1978541. The reversal of 1978539 is 9358791.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1978539 - 2³ = 1978531 is a prime.

It is a D-number.

It is a self number, because there is not a number n which added to its sum of digits gives 1978539.

It is not an unprimeable number, because it can be changed into a prime (1978531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 329754 + ... + 329759.

It is an arithmetic number, because the mean of its divisors is an integer number (659514).

2^1978539 is an apocalyptic number.

1978539 is a deficient number, since it is larger than the sum of its proper divisors (659517).

1978539 is an equidigital number, since it uses as much as digits as its factorization.

1978539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 659516.

The product of its digits is 68040, while the sum is 42.

The square root of 1978539 is about 1406.6054884011. The cubic root of 1978539 is about 125.5398306403.

The spelling of 1978539 in words is "one million, nine hundred seventy-eight thousand, five hundred thirty-nine".