21223287 has 6 divisors (see below), whose sum is σ = 30655872. Its totient is φ = 14148852.

The previous prime is 21223283. The next prime is 21223291. The reversal of 21223287 is 78232212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21223283) and next prime (21223291).

It is not a de Polignac number, because 21223287 - 2² = 21223283 is a prime.

It is a super-2 number, since 2×21223287² = 900855822168738, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21223287.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21223283) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1179063 + ... + 1179080.

It is an arithmetic number, because the mean of its divisors is an integer number (5109312).

Almost surely, 2^21223287 is an apocalyptic number.

21223287 is a deficient number, since it is larger than the sum of its proper divisors (9432585).

21223287 is a wasteful number, since it uses less digits than its factorization.

21223287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2358149 (or 2358146 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 21223287 is about 4606.8738858363. The cubic root of 21223287 is about 276.8668007260.

Adding to 21223287 its reverse (78232212), we get a palindrome (99455499).

The spelling of 21223287 in words is "twenty-one million, two hundred twenty-three thousand, two hundred eighty-seven".