206131621 has 2 divisors, whose sum is σ = 206131622. Its totient is φ = 206131620.

The previous prime is 206131609. The next prime is 206131631. The reversal of 206131621 is 126131602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 184144900 + 21986721 = 13570^2 + 4689^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206131621 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 206131592 and 206131601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206131631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103065810 + 103065811.

It is an arithmetic number, because the mean of its divisors is an integer number (103065811).

Almost surely, 2^206131621 is an apocalyptic number.

It is an amenable number.

206131621 is a deficient number, since it is larger than the sum of its proper divisors (1).

206131621 is an equidigital number, since it uses as much as digits as its factorization.

206131621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 206131621 is about 14357.2845970260. The cubic root of 206131621 is about 590.7198156935.

The spelling of 206131621 in words is "two hundred six million, one hundred thirty-one thousand, six hundred twenty-one".