21284263 has 24 divisors (see below), whose sum is σ = 28808864. Its totient is φ = 15301440.

The previous prime is 21284251. The next prime is 21284273. The reversal of 21284263 is 36248212.

It is not a de Polignac number, because 21284263 - 2⁹ = 21283751 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21284243) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10045 + ... + 11977.

Almost surely, 2^21284263 is an apocalyptic number.

21284263 is a deficient number, since it is larger than the sum of its proper divisors (7524601).

21284263 is a wasteful number, since it uses less digits than its factorization.

21284263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1975 (or 1964 counting only the distinct ones).

The product of its digits is 4608, while the sum is 28.

The square root of 21284263 is about 4613.4870759546. The cubic root of 21284263 is about 277.1316998100.

The spelling of 21284263 in words is "twenty-one million, two hundred eighty-four thousand, two hundred sixty-three".