21247049 has 2 divisors, whose sum is σ = 21247050. Its totient is φ = 21247048.

The previous prime is 21247033. The next prime is 21247063. The reversal of 21247049 is 94074212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16752649 + 4494400 = 4093^2 + 2120^2 .

It is a cyclic number.

It is not a de Polignac number, because 21247049 - 2⁴ = 21247033 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21247019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10623524 + 10623525.

It is an arithmetic number, because the mean of its divisors is an integer number (10623525).

Almost surely, 2^21247049 is an apocalyptic number.

It is an amenable number.

21247049 is a deficient number, since it is larger than the sum of its proper divisors (1).

21247049 is an equidigital number, since it uses as much as digits as its factorization.

21247049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21247049 is about 4609.4521366427. The cubic root of 21247049 is about 276.9700906508.

The spelling of 21247049 in words is "twenty-one million, two hundred forty-seven thousand, forty-nine".