206978831 has 2 divisors, whose sum is σ = 206978832. Its totient is φ = 206978830.

The previous prime is 206978813. The next prime is 206978839. The reversal of 206978831 is 138879602.

Together with previous prime (206978813) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206978831 is a prime.

It is a super-2 number, since 2×206978831² = 85680472964253122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206978839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103489415 + 103489416.

It is an arithmetic number, because the mean of its divisors is an integer number (103489416).

Almost surely, 2^206978831 is an apocalyptic number.

206978831 is a deficient number, since it is larger than the sum of its proper divisors (1).

206978831 is an equidigital number, since it uses as much as digits as its factorization.

206978831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 44.

The square root of 206978831 is about 14386.7588775235. The cubic root of 206978831 is about 591.5280042533.

The spelling of 206978831 in words is "two hundred six million, nine hundred seventy-eight thousand, eight hundred thirty-one".