21618116 has 24 divisors (see below), whose sum is σ = 40877760. Its totient is φ = 9944352.

The previous prime is 21618109. The next prime is 21618127. The reversal of 21618116 is 61181612.

It is a Harshad number since it is a multiple of its sum of digits (26).

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 7 ways as a sum of consecutive naturals, for example, 22355 + ... + 23301.

It is an arithmetic number, because the mean of its divisors is an integer number (1703240).

Almost surely, 2^21618116 is an apocalyptic number.

21618116 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21618116 is a deficient number, since it is larger than the sum of its proper divisors (19259644).

21618116 is a wasteful number, since it uses less digits than its factorization.

21618116 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1403 (or 1401 counting only the distinct ones).

The product of its digits is 576, while the sum is 26.

The square root of 21618116 is about 4649.5285782539. The cubic root of 21618116 is about 278.5731666151.

Adding to 21618116 its reverse (61181612), we get a palindrome (82799728).

The spelling of 21618116 in words is "twenty-one million, six hundred eighteen thousand, one hundred sixteen".