21006272 has 28 divisors (see below), whose sum is σ = 47640240. Its totient is φ = 9002496.

The previous prime is 21006263. The next prime is 21006277. The reversal of 21006272 is 27260012.

It is a tau number, because it is divible by the number of its divisors (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21006277) 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, 22997 + ... + 23892.

Almost surely, 2^21006272 is an apocalyptic number.

It is an amenable number.

21006272 is an abundant number, since it is smaller than the sum of its proper divisors (26633968).

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

21006272 is an equidigital number, since it uses as much as digits as its factorization.

21006272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46908 (or 46898 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21006272 is about 4583.2599751705. The cubic root of 21006272 is about 275.9198815270.

Adding to 21006272 its reverse (27260012), we get a palindrome (48266284).

The spelling of 21006272 in words is "twenty-one million, six thousand, two hundred seventy-two".