207688021 has 2 divisors, whose sum is σ = 207688022. Its totient is φ = 207688020.

The previous prime is 207687959. The next prime is 207688037. The reversal of 207688021 is 120886702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 206956996 + 731025 = 14386^2 + 855^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-207688021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (207688051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103844010 + 103844011.

It is an arithmetic number, because the mean of its divisors is an integer number (103844011).

Almost surely, 2^207688021 is an apocalyptic number.

It is an amenable number.

207688021 is a deficient number, since it is larger than the sum of its proper divisors (1).

207688021 is an equidigital number, since it uses as much as digits as its factorization.

207688021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 207688021 is about 14411.3851173300. The cubic root of 207688021 is about 592.2028357861.

The spelling of 207688021 in words is "two hundred seven million, six hundred eighty-eight thousand, twenty-one".