21118667 has 4 divisors (see below), whose sum is σ = 21128016. Its totient is φ = 21109320.

The previous prime is 21118663. The next prime is 21118717. The reversal of 21118667 is 76681112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21118667 - 2² = 21118663 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21118661) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1058 + ... + 6584.

It is an arithmetic number, because the mean of its divisors is an integer number (5282004).

Almost surely, 2^21118667 is an apocalyptic number.

21118667 is a deficient number, since it is larger than the sum of its proper divisors (9349).

21118667 is an equidigital number, since it uses as much as digits as its factorization.

21118667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9348.

The product of its digits is 4032, while the sum is 32.

The square root of 21118667 is about 4595.5050864948. The cubic root of 21118667 is about 276.4111136777.

Adding to 21118667 its reverse (76681112), we get a palindrome (97799779).

The spelling of 21118667 in words is "twenty-one million, one hundred eighteen thousand, six hundred sixty-seven".