21980911 has 2 divisors, whose sum is σ = 21980912. Its totient is φ = 21980910.

The previous prime is 21980909. The next prime is 21980947. The reversal of 21980911 is 11908912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21980911 - 2¹ = 21980909 is a prime.

Together with 21980909, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21980411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10990455 + 10990456.

It is an arithmetic number, because the mean of its divisors is an integer number (10990456).

Almost surely, 2^21980911 is an apocalyptic number.

21980911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21980911 is an equidigital number, since it uses as much as digits as its factorization.

21980911 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 31.

The square root of 21980911 is about 4688.3804239844. The cubic root of 21980911 is about 280.1228669951.

The spelling of 21980911 in words is "twenty-one million, nine hundred eighty thousand, nine hundred eleven".