21207472 has 120 divisors (see below), whose sum is σ = 52282368. Its totient is φ = 8236800.

The previous prime is 21207469. The next prime is 21207493. The reversal of 21207472 is 27470212.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 684097 + ... + 684127.

Almost surely, 2^21207472 is an apocalyptic number.

21207472 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21207472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26141184).

21207472 is an abundant number, since it is smaller than the sum of its proper divisors (31074896).

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

21207472 is a wasteful number, since it uses less digits than its factorization.

21207472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99 (or 80 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 21207472 is about 4605.1571091549. The cubic root of 21207472 is about 276.7980125042.

Adding to 21207472 its reverse (27470212), we get a palindrome (48677684).

The spelling of 21207472 in words is "twenty-one million, two hundred seven thousand, four hundred seventy-two".