21823866 has 12 divisors (see below), whose sum is σ = 47285082. Its totient is φ = 7274616.

The previous prime is 21823847. The next prime is 21823873. The reversal of 21823866 is 66832812.

It can be written as a sum of positive squares in only one way, i.e., 21818241 + 5625 = 4671^2 + 75^2 .

It is a super-2 number, since 2×21823866² = 952562254371912, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21823866.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 606201 + ... + 606236.

Almost surely, 2^21823866 is an apocalyptic number.

21823866 is an abundant number, since it is smaller than the sum of its proper divisors (25461216).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21823866 is a wasteful number, since it uses less digits than its factorization.

21823866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1212445 (or 1212442 counting only the distinct ones).

The product of its digits is 27648, while the sum is 36.

The square root of 21823866 is about 4671.6020806571. The cubic root of 21823866 is about 279.4541491582.

The spelling of 21823866 in words is "twenty-one million, eight hundred twenty-three thousand, eight hundred sixty-six".