21420528 has 20 divisors (see below), whose sum is σ = 55336488. Its totient is φ = 7140160.

The previous prime is 21420499. The next prime is 21420541. The reversal of 21420528 is 82502412.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 21420498 and 21420507.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 223083 + ... + 223178.

Almost surely, 2^21420528 is an apocalyptic number.

It is an amenable number.

21420528 is an abundant number, since it is smaller than the sum of its proper divisors (33915960).

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

21420528 is a wasteful number, since it uses less digits than its factorization.

21420528 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 446272 (or 446266 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21420528 is about 4628.2316277386. The cubic root of 21420528 is about 277.7218548874.

The spelling of 21420528 in words is "twenty-one million, four hundred twenty thousand, five hundred twenty-eight".