21430528 has 36 divisors (see below), whose sum is σ = 48892480. Its totient is φ = 9183744.

The previous prime is 21430481. The next prime is 21430529. The reversal of 21430528 is 82503412.

It is not an unprimeable number, because it can be changed into a prime (21430529) 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, 4188 + ... + 7771.

Almost surely, 2^21430528 is an apocalyptic number.

21430528 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21430528 is an abundant number, since it is smaller than the sum of its proper divisors (27461952).

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

21430528 is an equidigital number, since it uses as much as digits as its factorization.

21430528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11982 (or 11968 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 21430528 is about 4629.3118279070. The cubic root of 21430528 is about 277.7650655634.

The spelling of 21430528 in words is "twenty-one million, four hundred thirty thousand, five hundred twenty-eight".