206611821631 has 2 divisors, whose sum is σ = 206611821632. Its totient is φ = 206611821630.

The previous prime is 206611821553. The next prime is 206611821649. The reversal of 206611821631 is 136128116602.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 206611821631 - 2¹⁷ = 206611690559 is a prime.

It is a super-2 number, since 2×206611821631² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206611821131) 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, 103305910815 + 103305910816.

It is an arithmetic number, because the mean of its divisors is an integer number (103305910816).

Almost surely, 2^206611821631 is an apocalyptic number.

206611821631 is a deficient number, since it is larger than the sum of its proper divisors (1).

206611821631 is an equidigital number, since it uses as much as digits as its factorization.

206611821631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 37.

The spelling of 206611821631 in words is "two hundred six billion, six hundred eleven million, eight hundred twenty-one thousand, six hundred thirty-one".