221039857 has 2 divisors, whose sum is σ = 221039858. Its totient is φ = 221039856.

The previous prime is 221039849. The next prime is 221039869. The reversal of 221039857 is 758930122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 156975841 + 64064016 = 12529^2 + 8004^2 .

It is a cyclic number.

It is not a de Polignac number, because 221039857 - 2³ = 221039849 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (221039807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110519928 + 110519929.

It is an arithmetic number, because the mean of its divisors is an integer number (110519929).

Almost surely, 2^221039857 is an apocalyptic number.

It is an amenable number.

221039857 is a deficient number, since it is larger than the sum of its proper divisors (1).

221039857 is an equidigital number, since it uses as much as digits as its factorization.

221039857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 221039857 is about 14867.4092228606. The cubic root of 221039857 is about 604.6307032949.

Adding to 221039857 its reverse (758930122), we get a palindrome (979969979).

The spelling of 221039857 in words is "two hundred twenty-one million, thirty-nine thousand, eight hundred fifty-seven".