21214091 has 4 divisors (see below), whose sum is σ = 21249312. Its totient is φ = 21178872.

The previous prime is 21214087. The next prime is 21214111. The reversal of 21214091 is 19041212.

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 21214091 - 2² = 21214087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21214001) 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, 16691 + ... + 17916.

It is an arithmetic number, because the mean of its divisors is an integer number (5312328).

Almost surely, 2^21214091 is an apocalyptic number.

21214091 is a deficient number, since it is larger than the sum of its proper divisors (35221).

21214091 is an equidigital number, since it uses as much as digits as its factorization.

21214091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35220.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 21214091 is about 4605.8757039243. The cubic root of 21214091 is about 276.8268063726.

The spelling of 21214091 in words is "twenty-one million, two hundred fourteen thousand, ninety-one".