21954281 has 2 divisors, whose sum is σ = 21954282. Its totient is φ = 21954280.

The previous prime is 21954263. The next prime is 21954287. The reversal of 21954281 is 18245912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20475625 + 1478656 = 4525^2 + 1216^2 .

It is a cyclic number.

It is not a de Polignac number, because 21954281 - 2¹⁴ = 21937897 is a prime.

It is a super-2 number, since 2×21954281² = 963980908453922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21954287) 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, 10977140 + 10977141.

It is an arithmetic number, because the mean of its divisors is an integer number (10977141).

Almost surely, 2^21954281 is an apocalyptic number.

It is an amenable number.

21954281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21954281 is an equidigital number, since it uses as much as digits as its factorization.

21954281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 32.

The square root of 21954281 is about 4685.5395633801. The cubic root of 21954281 is about 280.0096977934.

The spelling of 21954281 in words is "twenty-one million, nine hundred fifty-four thousand, two hundred eighty-one".