205801009 has 2 divisors, whose sum is σ = 205801010. Its totient is φ = 205801008.

The previous prime is 205800983. The next prime is 205801039. The reversal of 205801009 is 900108502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 198725409 + 7075600 = 14097^2 + 2660^2 .

It is a cyclic number.

It is not a de Polignac number, because 205801009 - 2²⁵ = 172246577 is a prime.

It is not a weakly prime, because it can be changed into another prime (205801039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102900504 + 102900505.

It is an arithmetic number, because the mean of its divisors is an integer number (102900505).

Almost surely, 2^205801009 is an apocalyptic number.

It is an amenable number.

205801009 is a deficient number, since it is larger than the sum of its proper divisors (1).

205801009 is an equidigital number, since it uses as much as digits as its factorization.

205801009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 205801009 is about 14345.7662395565. The cubic root of 205801009 is about 590.4038305890.

The spelling of 205801009 in words is "two hundred five million, eight hundred one thousand, nine".