21818011 has 4 divisors (see below), whose sum is σ = 22282272. Its totient is φ = 21353752.

The previous prime is 21818003. The next prime is 21818029. The reversal of 21818011 is 11081812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21818011 - 2³ = 21818003 is a prime.

It is a super-2 number, since 2×21818011² = 952051207992242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21818051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 232060 + ... + 232153.

It is an arithmetic number, because the mean of its divisors is an integer number (5570568).

Almost surely, 2^21818011 is an apocalyptic number.

21818011 is a deficient number, since it is larger than the sum of its proper divisors (464261).

21818011 is an equidigital number, since it uses as much as digits as its factorization.

21818011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 464260.

The product of its (nonzero) digits is 128, while the sum is 22.

The square root of 21818011 is about 4670.9753799394. The cubic root of 21818011 is about 279.4291558719.

Adding to 21818011 its reverse (11081812), we get a palindrome (32899823).

The spelling of 21818011 in words is "twenty-one million, eight hundred eighteen thousand, eleven".