21249329 has 2 divisors, whose sum is σ = 21249330. Its totient is φ = 21249328.

The previous prime is 21249313. The next prime is 21249331. The reversal of 21249329 is 92394212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11916304 + 9333025 = 3452^2 + 3055^2 .

It is a cyclic number.

It is not a de Polignac number, because 21249329 - 2⁴ = 21249313 is a prime.

Together with 21249331, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21249295 and 21249304.

It is not a weakly prime, because it can be changed into another prime (21249829) 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 as a sum of consecutive naturals, namely, 10624664 + 10624665.

It is an arithmetic number, because the mean of its divisors is an integer number (10624665).

Almost surely, 2^21249329 is an apocalyptic number.

It is an amenable number.

21249329 is a deficient number, since it is larger than the sum of its proper divisors (1).

21249329 is an equidigital number, since it uses as much as digits as its factorization.

21249329 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 32.

The square root of 21249329 is about 4609.6994479033. The cubic root of 21249329 is about 276.9799974261.

The spelling of 21249329 in words is "twenty-one million, two hundred forty-nine thousand, three hundred twenty-nine".