21641268 has 48 divisors (see below), whose sum is σ = 55931904. Its totient is φ = 6457440.

The previous prime is 21641267. The next prime is 21641281. The reversal of 21641268 is 86214612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21641267) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7621 + ... + 10067.

It is an arithmetic number, because the mean of its divisors is an integer number (1165248).

Almost surely, 2^21641268 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 21641268, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27965952).

21641268 is an abundant number, since it is smaller than the sum of its proper divisors (34290636).

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

21641268 is a wasteful number, since it uses less digits than its factorization.

21641268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2532 (or 2530 counting only the distinct ones).

The product of its digits is 4608, while the sum is 30.

The square root of 21641268 is about 4652.0176267938. The cubic root of 21641268 is about 278.6725774509.

The spelling of 21641268 in words is "twenty-one million, six hundred forty-one thousand, two hundred sixty-eight".