1989251771 has 4 divisors (see below), whose sum is σ = 2142271152. Its totient is φ = 1836232392.

The previous prime is 1989251707. The next prime is 1989251779. The reversal of 1989251771 is 1771529891.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1771529891 = 79 ⋅22424429.

It is a cyclic number.

It is not a de Polignac number, because 1989251771 - 2⁶ = 1989251707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1989251779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76509671 + ... + 76509696.

It is an arithmetic number, because the mean of its divisors is an integer number (535567788).

Almost surely, 2^1989251771 is an apocalyptic number.

1989251771 is a deficient number, since it is larger than the sum of its proper divisors (153019381).

1989251771 is a wasteful number, since it uses less digits than its factorization.

1989251771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153019380.

The product of its digits is 317520, while the sum is 50.

The square root of 1989251771 is about 44601.0288110039. The cubic root of 1989251771 is about 1257.6600080177.

The spelling of 1989251771 in words is "one billion, nine hundred eighty-nine million, two hundred fifty-one thousand, seven hundred seventy-one".