21043428 has 48 divisors (see below), whose sum is σ = 56340480. Its totient is φ = 5988384.

The previous prime is 21043423. The next prime is 21043441. The reversal of 21043428 is 82434012.

It is a junction number, because it is equal to n+sod(n) for n = 21043398 and 21043407.

It is not an unprimeable number, because it can be changed into a prime (21043423) 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, 39975 + ... + 40497.

It is an arithmetic number, because the mean of its divisors is an integer number (1173760).

Almost surely, 2^21043428 is an apocalyptic number.

21043428 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21043428 is an abundant number, since it is smaller than the sum of its proper divisors (35297052).

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

21043428 is a wasteful number, since it uses less digits than its factorization.

21043428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1016 (or 1014 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 21043428 is about 4587.3116310100. The cubic root of 21043428 is about 276.0824685297.

The spelling of 21043428 in words is "twenty-one million, forty-three thousand, four hundred twenty-eight".