21042263 has 12 divisors (see below), whose sum is σ = 24137904. Its totient is φ = 18295200.

The previous prime is 21042251. The next prime is 21042283. The reversal of 21042263 is 36224012.

It is not a de Polignac number, because 21042263 - 2¹⁰ = 21041239 is a prime.

It is a super-2 number, since 2×21042263² = 885553664322338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042223) 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, 998 + ... + 6563.

It is an arithmetic number, because the mean of its divisors is an integer number (2011492).

Almost surely, 2^21042263 is an apocalyptic number.

21042263 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21042263 is a deficient number, since it is larger than the sum of its proper divisors (3095641).

21042263 is a wasteful number, since it uses less digits than its factorization.

21042263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7606 (or 7595 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 21042263 is about 4587.1846485617. The cubic root of 21042263 is about 276.0773736372.

Adding to 21042263 its reverse (36224012), we get a palindrome (57266275).

The spelling of 21042263 in words is "twenty-one million, forty-two thousand, two hundred sixty-three".