208257421 has 2 divisors, whose sum is σ = 208257422. Its totient is φ = 208257420.

The previous prime is 208257407. The next prime is 208257443. The reversal of 208257421 is 124752802.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 110544196 + 97713225 = 10514^2 + 9885^2 .

It is a cyclic number.

It is not a de Polignac number, because 208257421 - 2⁵ = 208257389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208257481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104128710 + 104128711.

It is an arithmetic number, because the mean of its divisors is an integer number (104128711).

Almost surely, 2^208257421 is an apocalyptic number.

It is an amenable number.

208257421 is a deficient number, since it is larger than the sum of its proper divisors (1).

208257421 is an equidigital number, since it uses as much as digits as its factorization.

208257421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8960, while the sum is 31.

The square root of 208257421 is about 14431.1268097817. The cubic root of 208257421 is about 592.7435387824.

The spelling of 208257421 in words is "two hundred eight million, two hundred fifty-seven thousand, four hundred twenty-one".