21012263 has 4 divisors (see below), whose sum is σ = 21580200. Its totient is φ = 20444328.

The previous prime is 21012259. The next prime is 21012281. The reversal of 21012263 is 36221012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21012263 - 2² = 21012259 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012283) 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, 283913 + ... + 283986.

It is an arithmetic number, because the mean of its divisors is an integer number (5395050).

Almost surely, 2^21012263 is an apocalyptic number.

21012263 is a deficient number, since it is larger than the sum of its proper divisors (567937).

21012263 is an equidigital number, since it uses as much as digits as its factorization.

21012263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567936.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21012263 is about 4583.9135026743. The cubic root of 21012263 is about 275.9461098663.

Adding to 21012263 its reverse (36221012), we get a palindrome (57233275).

The spelling of 21012263 in words is "twenty-one million, twelve thousand, two hundred sixty-three".