21818826 has 36 divisors (see below), whose sum is σ = 48821526. Its totient is φ = 7037280.

The previous prime is 21818809. The next prime is 21818833. The reversal of 21818826 is 62881812.

It can be written as a sum of positive squares in 3 ways, for example, as 9603801 + 12215025 = 3099^2 + 3495^2 .

It is a super-2 number, since 2×21818826² = 952122336036552, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 120456 + ... + 120636.

Almost surely, 2^21818826 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21818826, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24410763).

21818826 is an abundant number, since it is smaller than the sum of its proper divisors (27002700).

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

21818826 is a wasteful number, since it uses less digits than its factorization.

21818826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407 (or 223 counting only the distinct ones).

The product of its digits is 12288, while the sum is 36.

The square root of 21818826 is about 4671.0626200041. The cubic root of 21818826 is about 279.4326351369.

It can be divided in two parts, 218 and 18826, that added together give a square (19044 = 138²).

The spelling of 21818826 in words is "twenty-one million, eight hundred eighteen thousand, eight hundred twenty-six".