21263305 has 24 divisors (see below), whose sum is σ = 30205440. Its totient is φ = 14323680.

The previous prime is 21263279. The next prime is 21263309. The reversal of 21263305 is 50336212.

It is not a de Polignac number, because 21263305 - 2¹⁵ = 21230537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21263309) 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, 13720 + ... + 15190.

It is an arithmetic number, because the mean of its divisors is an integer number (1258560).

Almost surely, 2^21263305 is an apocalyptic number.

It is an amenable number.

21263305 is a deficient number, since it is larger than the sum of its proper divisors (8942135).

21263305 is a wasteful number, since it uses less digits than its factorization.

21263305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1549 (or 1542 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 21263305 is about 4611.2151326955. The cubic root of 21263305 is about 277.0407087403.

Adding to 21263305 its reverse (50336212), we get a palindrome (71599517).

The spelling of 21263305 in words is "twenty-one million, two hundred sixty-three thousand, three hundred five".