21428968 has 32 divisors (see below), whose sum is σ = 44284320. Its totient is φ = 9640000.

The previous prime is 21428963. The next prime is 21428969. The reversal of 21428968 is 86982412.

It is a self number, because there is not a number n which added to its sum of digits gives 21428968.

It is not an unprimeable number, because it can be changed into a prime (21428963) 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, 7683 + ... + 10093.

It is an arithmetic number, because the mean of its divisors is an integer number (1383885).

Almost surely, 2^21428968 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 21428968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22142160).

21428968 is an abundant number, since it is smaller than the sum of its proper divisors (22855352).

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

21428968 is a wasteful number, since it uses less digits than its factorization.

21428968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2529 (or 2525 counting only the distinct ones).

The product of its digits is 55296, while the sum is 40.

The square root of 21428968 is about 4629.1433332745. The cubic root of 21428968 is about 277.7583255830.

The spelling of 21428968 in words is "twenty-one million, four hundred twenty-eight thousand, nine hundred sixty-eight".