21894281 has 2 divisors, whose sum is σ = 21894282. Its totient is φ = 21894280.

The previous prime is 21894259. The next prime is 21894293. The reversal of 21894281 is 18249812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18318400 + 3575881 = 4280^2 + 1891^2 .

It is a cyclic number.

It is not a de Polignac number, because 21894281 - 2¹⁰ = 21893257 is a prime.

It is a super-2 number, since 2×21894281² = 958719081013922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21894211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10947140 + 10947141.

It is an arithmetic number, because the mean of its divisors is an integer number (10947141).

Almost surely, 2^21894281 is an apocalyptic number.

It is an amenable number.

21894281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21894281 is an equidigital number, since it uses as much as digits as its factorization.

21894281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 35.

The square root of 21894281 is about 4679.1325050697. The cubic root of 21894281 is about 279.7543806913.

The spelling of 21894281 in words is "twenty-one million, eight hundred ninety-four thousand, two hundred eighty-one".