21153249 has 12 divisors (see below), whose sum is σ = 32905236. Its totient is φ = 13017312.

The previous prime is 21153227. The next prime is 21153257. The reversal of 21153249 is 94235112.

It can be written as a sum of positive squares in 2 ways, for example, as 2387025 + 18766224 = 1545^2 + 4332^2 .

It is not a de Polignac number, because 21153249 - 2⁹ = 21152737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21153259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 90282 + ... + 90515.

It is an arithmetic number, because the mean of its divisors is an integer number (2742103).

Almost surely, 2^21153249 is an apocalyptic number.

It is an amenable number.

21153249 is a deficient number, since it is larger than the sum of its proper divisors (11751987).

21153249 is a wasteful number, since it uses less digits than its factorization.

21153249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180816 (or 180813 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 21153249 is about 4599.2661371136. The cubic root of 21153249 is about 276.5619065964.

The spelling of 21153249 in words is "twenty-one million, one hundred fifty-three thousand, two hundred forty-nine".