21324728 has 16 divisors (see below), whose sum is σ = 41065080. Its totient is φ = 10374048.

The previous prime is 21324727. The next prime is 21324733. The reversal of 21324728 is 82742312.

It is a self number, because there is not a number n which added to its sum of digits gives 21324728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21324727) 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, 35726 + ... + 36317.

Almost surely, 2^21324728 is an apocalyptic number.

It is an amenable number.

21324728 is a deficient number, since it is larger than the sum of its proper divisors (19740352).

21324728 is a wasteful number, since it uses less digits than its factorization.

21324728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72086 (or 72082 counting only the distinct ones).

The product of its digits is 5376, while the sum is 29.

The square root of 21324728 is about 4617.8705048973. The cubic root of 21324728 is about 277.3072134445.

The spelling of 21324728 in words is "twenty-one million, three hundred twenty-four thousand, seven hundred twenty-eight".