21481771 has 2 divisors, whose sum is σ = 21481772. Its totient is φ = 21481770.

The previous prime is 21481769. The next prime is 21481787. The reversal of 21481771 is 17718412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21481771 - 2¹ = 21481769 is a prime.

It is a super-2 number, since 2×21481771² = 922932970592882, which contains 22 as substring.

Together with 21481769, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21481751) 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 as a sum of consecutive naturals, namely, 10740885 + 10740886.

It is an arithmetic number, because the mean of its divisors is an integer number (10740886).

Almost surely, 2^21481771 is an apocalyptic number.

21481771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21481771 is an equidigital number, since it uses as much as digits as its factorization.

21481771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3136, while the sum is 31.

The square root of 21481771 is about 4634.8431472920. The cubic root of 21481771 is about 277.9862793635.

The spelling of 21481771 in words is "twenty-one million, four hundred eighty-one thousand, seven hundred seventy-one".