989721828 has 60 divisors (see below), whose sum is σ = 2629796092. Its totient is φ = 324492480.

The previous prime is 989721823. The next prime is 989721833. The reversal of 989721828 is 828127989.

It is an interprime number because it is at equal distance from previous prime (989721823) and next prime (989721833).

It can be written as a sum of positive squares in 2 ways, for example, as 380718144 + 609003684 = 19512^2 + 24678^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (989721823) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5275 + ... + 44802.

Almost surely, 2^989721828 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 989721828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1314898046).

989721828 is an abundant number, since it is smaller than the sum of its proper divisors (1640074264).

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

989721828 is a wasteful number, since it uses less digits than its factorization.

989721828 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50154 (or 50143 counting only the distinct ones).

The product of its digits is 1161216, while the sum is 54.

The square root of 989721828 is about 31459.8446912886. The cubic root of 989721828 is about 996.5621373107.

The spelling of 989721828 in words is "nine hundred eighty-nine million, seven hundred twenty-one thousand, eight hundred twenty-eight".