21428364 has 48 divisors (see below), whose sum is σ = 55254528. Its totient is φ = 6428928.

The previous prime is 21428339. The next prime is 21428383. The reversal of 21428364 is 46382412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2409 + ... + 6975.

It is an arithmetic number, because the mean of its divisors is an integer number (1151136).

Almost surely, 2^21428364 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 21428364, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27627264).

21428364 is an abundant number, since it is smaller than the sum of its proper divisors (33826164).

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

21428364 is a wasteful number, since it uses less digits than its factorization.

21428364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4614 (or 4612 counting only the distinct ones).

The product of its digits is 9216, while the sum is 30.

The square root of 21428364 is about 4629.0780939621. The cubic root of 21428364 is about 277.7557159130.

The spelling of 21428364 in words is "twenty-one million, four hundred twenty-eight thousand, three hundred sixty-four".