21430272 has 68 divisors (see below), whose sum is σ = 57671240. Its totient is φ = 7077888.

The previous prime is 21430259. The next prime is 21430291. The reversal of 21430272 is 27203412.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 196554 + ... + 196662.

Almost surely, 2^21430272 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21430272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28835620).

21430272 is an abundant number, since it is smaller than the sum of its proper divisors (36240968).

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

21430272 is an frugal number, since it uses more digits than its factorization.

21430272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 21430272 is about 4629.2841779264. The cubic root of 21430272 is about 277.7639595378.

Adding to 21430272 its reverse (27203412), we get a palindrome (48633684).

The spelling of 21430272 in words is "twenty-one million, four hundred thirty thousand, two hundred seventy-two".