21618011 has 8 divisors (see below), whose sum is σ = 22278240. Its totient is φ = 20967232.

The previous prime is 21618007. The next prime is 21618041. The reversal of 21618011 is 11081612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21618011 - 2² = 21618007 is a prime.

It is a super-2 number, since 2×21618011² = 934676799192242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21618041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2426 + ... + 7008.

It is an arithmetic number, because the mean of its divisors is an integer number (2784780).

Almost surely, 2^21618011 is an apocalyptic number.

21618011 is a deficient number, since it is larger than the sum of its proper divisors (660229).

21618011 is an equidigital number, since it uses as much as digits as its factorization.

21618011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4725.

The product of its (nonzero) digits is 96, while the sum is 20.

The square root of 21618011 is about 4649.5172867729. The cubic root of 21618011 is about 278.5727156010.

Adding to 21618011 its reverse (11081612), we get a palindrome (32699623).

The spelling of 21618011 in words is "twenty-one million, six hundred eighteen thousand, eleven".