21305149 has 2 divisors, whose sum is σ = 21305150. Its totient is φ = 21305148.

The previous prime is 21305113. The next prime is 21305159. The reversal of 21305149 is 94150312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16957924 + 4347225 = 4118^2 + 2085^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21305149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21305159) 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, 10652574 + 10652575.

It is an arithmetic number, because the mean of its divisors is an integer number (10652575).

Almost surely, 2^21305149 is an apocalyptic number.

It is an amenable number.

21305149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21305149 is an equidigital number, since it uses as much as digits as its factorization.

21305149 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21305149 is about 4615.7501015545. The cubic root of 21305149 is about 277.2223188810. Note that the first 3 decimals are identical.

The spelling of 21305149 in words is "twenty-one million, three hundred five thousand, one hundred forty-nine".