21403228 has 24 divisors (see below), whose sum is σ = 46698624. Its totient is φ = 8338800.

The previous prime is 21403211. The next prime is 21403229. The reversal of 21403228 is 82230412.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21403199 and 21403208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21403229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34438 + ... + 35053.

It is an arithmetic number, because the mean of its divisors is an integer number (1945776).

Almost surely, 2^21403228 is an apocalyptic number.

21403228 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21403228 is an abundant number, since it is smaller than the sum of its proper divisors (25295396).

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

21403228 is a wasteful number, since it uses less digits than its factorization.

21403228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69513 (or 69511 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 21403228 is about 4626.3622858570. The cubic root of 21403228 is about 277.6470686493.

The spelling of 21403228 in words is "twenty-one million, four hundred three thousand, two hundred twenty-eight".