847249721 has 2 divisors, whose sum is σ = 847249722. Its totient is φ = 847249720.

The previous prime is 847249709. The next prime is 847249727. The reversal of 847249721 is 127942748.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 570493225 + 276756496 = 23885^2 + 16636^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-847249721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (847249727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 423624860 + 423624861.

It is an arithmetic number, because the mean of its divisors is an integer number (423624861).

Almost surely, 2^847249721 is an apocalyptic number.

It is an amenable number.

847249721 is a deficient number, since it is larger than the sum of its proper divisors (1).

847249721 is an equidigital number, since it uses as much as digits as its factorization.

847249721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 225792, while the sum is 44.

The square root of 847249721 is about 29107.5543630859. The cubic root of 847249721 is about 946.2454658634.

The spelling of 847249721 in words is "eight hundred forty-seven million, two hundred forty-nine thousand, seven hundred twenty-one".