21215268 has 36 divisors (see below), whose sum is σ = 53790828. Its totient is φ = 7050240.

The previous prime is 21215263. The next prime is 21215287. The reversal of 21215268 is 86251212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 2965284 + 18249984 = 1722^2 + 4272^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (21215261) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14908 + ... + 16268.

Almost surely, 2^21215268 is an apocalyptic number.

It is an amenable number.

21215268 is an abundant number, since it is smaller than the sum of its proper divisors (32575560).

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

21215268 is a wasteful number, since it uses less digits than its factorization.

21215268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1804 (or 1799 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 21215268 is about 4606.0034737286. The cubic root of 21215268 is about 276.8319259120.

The spelling of 21215268 in words is "twenty-one million, two hundred fifteen thousand, two hundred sixty-eight".