21821366 has 24 divisors (see below), whose sum is σ = 38450376. Its totient is φ = 9260160.

The previous prime is 21821363. The next prime is 21821383. The reversal of 21821366 is 66312812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21821363) 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, 9446 + ... + 11526.

It is an arithmetic number, because the mean of its divisors is an integer number (1602099).

Almost surely, 2^21821366 is an apocalyptic number.

21821366 is a deficient number, since it is larger than the sum of its proper divisors (16629010).

21821366 is a wasteful number, since it uses less digits than its factorization.

21821366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2204 (or 2197 counting only the distinct ones).

The product of its digits is 3456, while the sum is 29.

The square root of 21821366 is about 4671.3344988344. The cubic root of 21821366 is about 279.4434779347.

The spelling of 21821366 in words is "twenty-one million, eight hundred twenty-one thousand, three hundred sixty-six".