21281149 has 2 divisors, whose sum is σ = 21281150. Its totient is φ = 21281148.

The previous prime is 21281137. The next prime is 21281153. The reversal of 21281149 is 94118212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11009124 + 10272025 = 3318^2 + 3205^2 .

It is a cyclic number.

It is not a de Polignac number, because 21281149 - 2⁷ = 21281021 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21284149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10640574 + 10640575.

It is an arithmetic number, because the mean of its divisors is an integer number (10640575).

Almost surely, 2^21281149 is an apocalyptic number.

It is an amenable number.

21281149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21281149 is an equidigital number, since it uses as much as digits as its factorization.

21281149 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 28.

The square root of 21281149 is about 4613.1495748566. The cubic root of 21281149 is about 277.1181838741.

The spelling of 21281149 in words is "twenty-one million, two hundred eighty-one thousand, one hundred forty-nine".