21740249 has 2 divisors, whose sum is σ = 21740250. Its totient is φ = 21740248.

The previous prime is 21740239. The next prime is 21740281. The reversal of 21740249 is 94204712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21715600 + 24649 = 4660^2 + 157^2 .

It is a cyclic number.

It is not a de Polignac number, because 21740249 - 2⁴ = 21740233 is a prime.

It is not a weakly prime, because it can be changed into another prime (21740219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10870124 + 10870125.

It is an arithmetic number, because the mean of its divisors is an integer number (10870125).

Almost surely, 2^21740249 is an apocalyptic number.

It is an amenable number.

21740249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21740249 is an equidigital number, since it uses as much as digits as its factorization.

21740249 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 21740249 is about 4662.6439924146. The cubic root of 21740249 is about 279.0967877177.

The spelling of 21740249 in words is "twenty-one million, seven hundred forty thousand, two hundred forty-nine".