21321528 has 16 divisors (see below), whose sum is σ = 53303880. Its totient is φ = 7107168.

The previous prime is 21321527. The next prime is 21321539. The reversal of 21321528 is 82512312.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 888397 = 21321528 / (2 + 1 + 3 + 2 + 1 + 5 + 2 + 8).

It is a junction number, because it is equal to n+sod(n) for n = 21321498 and 21321507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321523) 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, 444175 + ... + 444222.

Almost surely, 2^21321528 is an apocalyptic number.

It is an amenable number.

21321528 is an abundant number, since it is smaller than the sum of its proper divisors (31982352).

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

21321528 is a wasteful number, since it uses less digits than its factorization.

21321528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888406 (or 888402 counting only the distinct ones).

The product of its digits is 960, while the sum is 24.

The square root of 21321528 is about 4617.5240118488. The cubic root of 21321528 is about 277.2933417947.

The spelling of 21321528 in words is "twenty-one million, three hundred twenty-one thousand, five hundred twenty-eight".