1989917279 has 4 divisors (see below), whose sum is σ = 2274191184. Its totient is φ = 1705643376.

The previous prime is 1989917221. The next prime is 1989917287. The reversal of 1989917279 is 9727199891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9727199891 = 19 ⋅511957889.

It is a cyclic number.

It is not a de Polignac number, because 1989917279 - 2⁸ = 1989917023 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 (1989911279) 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, 142136942 + ... + 142136955.

It is an arithmetic number, because the mean of its divisors is an integer number (568547796).

Almost surely, 2^1989917279 is an apocalyptic number.

1989917279 is a deficient number, since it is larger than the sum of its proper divisors (284273905).

1989917279 is an equidigital number, since it uses as much as digits as its factorization.

1989917279 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284273904.

The product of its digits is 5143824, while the sum is 62.

The square root of 1989917279 is about 44608.4888670307. The cubic root of 1989917279 is about 1257.8002432371.

The spelling of 1989917279 in words is "one billion, nine hundred eighty-nine million, nine hundred seventeen thousand, two hundred seventy-nine".