21289763 has 24 divisors (see below), whose sum is σ = 25478544. Its totient is φ = 17625600.

The previous prime is 21289757. The next prime is 21289769. The reversal of 21289763 is 36798212.

It is an interprime number because it is at equal distance from previous prime (21289757) and next prime (21289769).

It is not a de Polignac number, because 21289763 - 2¹⁰ = 21288739 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21289769) 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, 117533 + ... + 117713.

It is an arithmetic number, because the mean of its divisors is an integer number (1061606).

Almost surely, 2^21289763 is an apocalyptic number.

21289763 is a deficient number, since it is larger than the sum of its proper divisors (4188781).

21289763 is a wasteful number, since it uses less digits than its factorization.

21289763 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263 (or 246 counting only the distinct ones).

The product of its digits is 36288, while the sum is 38.

The square root of 21289763 is about 4614.0831158530. The cubic root of 21289763 is about 277.1555686668.

The spelling of 21289763 in words is "twenty-one million, two hundred eighty-nine thousand, seven hundred sixty-three".