21420067 has 4 divisors (see below), whose sum is σ = 22158720. Its totient is φ = 20681416.

The previous prime is 21420043. The next prime is 21420073. The reversal of 21420067 is 76002412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21420067 - 2⁷ = 21419939 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21420037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 369283 + ... + 369340.

It is an arithmetic number, because the mean of its divisors is an integer number (5539680).

Almost surely, 2^21420067 is an apocalyptic number.

21420067 is a deficient number, since it is larger than the sum of its proper divisors (738653).

21420067 is an equidigital number, since it uses as much as digits as its factorization.

21420067 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 738652.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 21420067 is about 4628.1818244317. The cubic root of 21420067 is about 277.7198625510.

Adding to 21420067 its reverse (76002412), we get a palindrome (97422479).

The spelling of 21420067 in words is "twenty-one million, four hundred twenty thousand, sixty-seven".