921228 has 48 divisors (see below), whose sum is σ = 2682624. Its totient is φ = 239040.

The previous prime is 921223. The next prime is 921233. The reversal of 921228 is 822129.

It is an interprime number because it is at equal distance from previous prime (921223) and next prime (921233).

It is a super-2 number, since 2×921228² = 1697322055968, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 921198 and 921207.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 921228.

It is not an unprimeable number, because it can be changed into a prime (921223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 426 + ... + 1422.

It is an arithmetic number, because the mean of its divisors is an integer number (55888).

2⁹²¹²²⁸ 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 921228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1341312).

921228 is an abundant number, since it is smaller than the sum of its proper divisors (1761396).

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

921228 is a wasteful number, since it uses less digits than its factorization.

921228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022 (or 1020 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 921228 is about 959.8062304445. The cubic root of 921228 is about 97.3021365378.

Subtracting from 921228 its reverse (822129), we obtain a palindrome (99099).

The spelling of 921228 in words is "nine hundred twenty-one thousand, two hundred twenty-eight".