207870021 has 18 divisors (see below), whose sum is σ = 313886118. Its totient is φ = 132551760.

The previous prime is 207870017. The next prime is 207870043. The reversal of 207870021 is 120078702.

It can be written as a sum of positive squares in only one way, i.e., 202037796 + 5832225 = 14214^2 + 2415^2 .

It is not a de Polignac number, because 207870021 - 2² = 207870017 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (207870721) 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 in 17 ways as a sum of consecutive naturals, for example, 17070 + ... + 26591.

Almost surely, 2^207870021 is an apocalyptic number.

It is an amenable number.

207870021 is a deficient number, since it is larger than the sum of its proper divisors (106016097).

207870021 is a wasteful number, since it uses less digits than its factorization.

207870021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43713 (or 43687 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

The square root of 207870021 is about 14417.6981866039. The cubic root of 207870021 is about 592.3757705684.

The spelling of 207870021 in words is "two hundred seven million, eight hundred seventy thousand, twenty-one".