21289766 has 16 divisors (see below), whose sum is σ = 35078400. Its totient is φ = 9645768.

The previous prime is 21289757. The next prime is 21289769. The reversal of 21289766 is 66798212.

It is a congruent 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 7 ways as a sum of consecutive naturals, for example, 11306 + ... + 13053.

It is an arithmetic number, because the mean of its divisors is an integer number (2192400).

Almost surely, 2^21289766 is an apocalyptic number.

21289766 is a deficient number, since it is larger than the sum of its proper divisors (13788634).

21289766 is a wasteful number, since it uses less digits than its factorization.

21289766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24403.

The product of its digits is 72576, while the sum is 41.

The square root of 21289766 is about 4614.0834409447. The cubic root of 21289766 is about 277.1555816850.

The spelling of 21289766 in words is "twenty-one million, two hundred eighty-nine thousand, seven hundred sixty-six".