21530464 has 12 divisors (see below), whose sum is σ = 42388164. Its totient is φ = 10765216.

The previous prime is 21530459. The next prime is 21530471. The reversal of 21530464 is 46403512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 336382 + ... + 336445.

It is an arithmetic number, because the mean of its divisors is an integer number (3532347).

Almost surely, 2^21530464 is an apocalyptic number.

It is an amenable number.

21530464 is a deficient number, since it is larger than the sum of its proper divisors (20857700).

21530464 is an equidigital number, since it uses as much as digits as its factorization.

21530464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 672837 (or 672829 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21530464 is about 4640.0931025142. The cubic root of 21530464 is about 278.1961591940.

Adding to 21530464 its reverse (46403512), we get a palindrome (67933976).

The spelling of 21530464 in words is "twenty-one million, five hundred thirty thousand, four hundred sixty-four".