21432530 has 32 divisors (see below), whose sum is σ = 44319744. Its totient is φ = 7310016.

The previous prime is 21432493. The next prime is 21432539. The reversal of 21432530 is 3523412.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21432539) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14924 + ... + 16296.

It is an arithmetic number, because the mean of its divisors is an integer number (1384992).

Almost surely, 2^21432530 is an apocalyptic number.

21432530 is an abundant number, since it is smaller than the sum of its proper divisors (22887214).

21432530 is a wasteful number, since it uses less digits than its factorization.

21432530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1610.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21432530 is about 4629.5280537005. The cubic root of 21432530 is about 277.7737147258.

Adding to 21432530 its reverse (3523412), we get a palindrome (24955942).

The spelling of 21432530 in words is "twenty-one million, four hundred thirty-two thousand, five hundred thirty".