1205913809 has 2 divisors, whose sum is σ = 1205913810. Its totient is φ = 1205913808.

The previous prime is 1205913799. The next prime is 1205913817. The reversal of 1205913809 is 9083195021.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1043096209 + 162817600 = 32297^2 + 12760^2 .

It is a cyclic number.

It is not a de Polignac number, because 1205913809 - 2¹² = 1205909713 is a prime.

It is a super-2 number, since 2×1205913809² = 2908456229473776962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1205913859) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 602956904 + 602956905.

It is an arithmetic number, because the mean of its divisors is an integer number (602956905).

Almost surely, 2^1205913809 is an apocalyptic number.

It is an amenable number.

1205913809 is a deficient number, since it is larger than the sum of its proper divisors (1).

1205913809 is an equidigital number, since it uses as much as digits as its factorization.

1205913809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 1205913809 is about 34726.2697248063. The cubic root of 1205913809 is about 1064.4013648796.

The spelling of 1205913809 in words is "one billion, two hundred five million, nine hundred thirteen thousand, eight hundred nine".