1979989 has 4 divisors (see below), whose sum is σ = 2160000. Its totient is φ = 1799980.

The previous prime is 1979947. The next prime is 1979993. The reversal of 1979989 is 9899791.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9899791 = 11 ⋅899981.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1979989 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 (1979189) 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, 89989 + ... + 90010.

It is an arithmetic number, because the mean of its divisors is an integer number (540000).

2^1979989 is an apocalyptic number.

It is an amenable number.

1979989 is a deficient number, since it is larger than the sum of its proper divisors (180011).

1979989 is a wasteful number, since it uses less digits than its factorization.

1979989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180010.

The product of its digits is 367416, while the sum is 52.

The square root of 1979989 is about 1407.1208192618. The cubic root of 1979989 is about 125.5704910256.

It can be divided in two parts, 1979 and 989, that multiplied together give a triangular number (1957231 = T₁₉₇₈).

The spelling of 1979989 in words is "one million, nine hundred seventy-nine thousand, nine hundred eighty-nine".