21449428 has 72 divisors (see below), whose sum is σ = 50884736. Its totient is φ = 7698240.

The previous prime is 21449413. The next prime is 21449431. The reversal of 21449428 is 82494412.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21449393 and 21449402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 43801 + ... + 44287.

Almost surely, 2^21449428 is an apocalyptic number.

21449428 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21449428, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25442368).

21449428 is an abundant number, since it is smaller than the sum of its proper divisors (29435308).

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

21449428 is a wasteful number, since it uses less digits than its factorization.

21449428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 533 (or 520 counting only the distinct ones).

The product of its digits is 18432, while the sum is 34.

The square root of 21449428 is about 4631.3527181591. The cubic root of 21449428 is about 277.8466970443.

The spelling of 21449428 in words is "twenty-one million, four hundred forty-nine thousand, four hundred twenty-eight".