21207667 has 12 divisors (see below), whose sum is σ = 24109680. Its totient is φ = 18541872.

The previous prime is 21207649. The next prime is 21207673. The reversal of 21207667 is 76670212.

It is not a de Polignac number, because 21207667 - 2⁷ = 21207539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21207607) 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 11 ways as a sum of consecutive naturals, for example, 2434 + ... + 6952.

It is an arithmetic number, because the mean of its divisors is an integer number (2009140).

Almost surely, 2^21207667 is an apocalyptic number.

21207667 is a deficient number, since it is larger than the sum of its proper divisors (2902013).

21207667 is a wasteful number, since it uses less digits than its factorization.

21207667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4570 (or 4551 counting only the distinct ones).

The product of its (nonzero) digits is 7056, while the sum is 31.

The square root of 21207667 is about 4605.1782810224. The cubic root of 21207667 is about 276.7988608758.

Adding to 21207667 its reverse (76670212), we get a palindrome (97877879).

The spelling of 21207667 in words is "twenty-one million, two hundred seven thousand, six hundred sixty-seven".