208638961 has 2 divisors, whose sum is σ = 208638962. Its totient is φ = 208638960.

The previous prime is 208638917. The next prime is 208638973. The reversal of 208638961 is 169836802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 165276736 + 43362225 = 12856^2 + 6585^2 .

It is a cyclic number.

It is not a de Polignac number, because 208638961 - 2¹⁷ = 208507889 is a prime.

It is not a weakly prime, because it can be changed into another prime (208638901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104319480 + 104319481.

It is an arithmetic number, because the mean of its divisors is an integer number (104319481).

Almost surely, 2^208638961 is an apocalyptic number.

It is an amenable number.

208638961 is a deficient number, since it is larger than the sum of its proper divisors (1).

208638961 is an equidigital number, since it uses as much as digits as its factorization.

208638961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 124416, while the sum is 43.

The square root of 208638961 is about 14444.3401026146. The cubic root of 208638961 is about 593.1052984403.

The spelling of 208638961 in words is "two hundred eight million, six hundred thirty-eight thousand, nine hundred sixty-one".