21901211 has 2 divisors, whose sum is σ = 21901212. Its totient is φ = 21901210.

The previous prime is 21901207. The next prime is 21901247. The reversal of 21901211 is 11210912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21901211 - 2² = 21901207 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21901211.

It is not a weakly prime, because it can be changed into another prime (21901291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10950605 + 10950606.

It is an arithmetic number, because the mean of its divisors is an integer number (10950606).

Almost surely, 2^21901211 is an apocalyptic number.

21901211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21901211 is an equidigital number, since it uses as much as digits as its factorization.

21901211 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 17.

The square root of 21901211 is about 4679.8729683614. The cubic root of 21901211 is about 279.7838936243.

The spelling of 21901211 in words is "twenty-one million, nine hundred one thousand, two hundred eleven".