21618101 has 8 divisors (see below), whose sum is σ = 23509080. Its totient is φ = 19795968.

The previous prime is 21618059. The next prime is 21618109. The reversal of 21618101 is 10181612.

It can be written as a sum of positive squares in 4 ways, for example, as 17098225 + 4519876 = 4135^2 + 2126^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21618101 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21618109) 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, 16556 + ... + 17813.

It is an arithmetic number, because the mean of its divisors is an integer number (2938635).

Almost surely, 2^21618101 is an apocalyptic number.

It is an amenable number.

21618101 is a deficient number, since it is larger than the sum of its proper divisors (1890979).

21618101 is a wasteful number, since it uses less digits than its factorization.

21618101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34423.

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

The square root of 21618101 is about 4649.5269651869. The cubic root of 21618101 is about 278.5731021846.

Adding to 21618101 its reverse (10181612), we get a palindrome (31799713).

The spelling of 21618101 in words is "twenty-one million, six hundred eighteen thousand, one hundred one".