21428832 has 24 divisors (see below), whose sum is σ = 56250936. Its totient is φ = 7142912.

The previous prime is 21428831. The next prime is 21428861. The reversal of 21428832 is 23882412.

It is a tau number, because it is divible by the number of its divisors (24).

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21428832.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21428831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111513 + ... + 111704.

It is an arithmetic number, because the mean of its divisors is an integer number (2343789).

Almost surely, 2^21428832 is an apocalyptic number.

It is an amenable number.

21428832 is an abundant number, since it is smaller than the sum of its proper divisors (34822104).

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

21428832 is a wasteful number, since it uses less digits than its factorization.

21428832 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223230 (or 223222 counting only the distinct ones).

The product of its digits is 6144, while the sum is 30.

The square root of 21428832 is about 4629.1286437082. The cubic root of 21428832 is about 277.7577379795.

The spelling of 21428832 in words is "twenty-one million, four hundred twenty-eight thousand, eight hundred thirty-two".