21813066 has 48 divisors (see below), whose sum is σ = 52835328. Its totient is φ = 6446400.

The previous prime is 21813059. The next prime is 21813073. The reversal of 21813066 is 66031812.

It is an interprime number because it is at equal distance from previous prime (21813059) and next prime (21813073).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6775 + ... + 9461.

It is an arithmetic number, because the mean of its divisors is an integer number (1100736).

Almost surely, 2^21813066 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21813066, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26417664).

21813066 is an abundant number, since it is smaller than the sum of its proper divisors (31022262).

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

21813066 is a wasteful number, since it uses less digits than its factorization.

21813066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2747 (or 2744 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21813066 is about 4670.4460172450. The cubic root of 21813066 is about 279.4080436269.

Adding to 21813066 its reverse (66031812), we get a palindrome (87844878).

The spelling of 21813066 in words is "twenty-one million, eight hundred thirteen thousand, sixty-six".