1209745205 has 4 divisors (see below), whose sum is σ = 1451694252. Its totient is φ = 967796160.

The previous prime is 1209745171. The next prime is 1209745213. The reversal of 1209745205 is 5025479021.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 885241009 + 324504196 = 29753^2 + 18014^2 .

It is not a de Polignac number, because 1209745205 - 2¹⁰ = 1209744181 is a prime.

It is a super-2 number, since 2×1209745205² = 2926966922040984050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120974516 + ... + 120974525.

It is an arithmetic number, because the mean of its divisors is an integer number (362923563).

Almost surely, 2^1209745205 is an apocalyptic number.

It is an amenable number.

1209745205 is a deficient number, since it is larger than the sum of its proper divisors (241949047).

1209745205 is an equidigital number, since it uses as much as digits as its factorization.

1209745205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241949046.

The product of its (nonzero) digits is 25200, while the sum is 35.

The square root of 1209745205 is about 34781.3916484088. The cubic root of 1209745205 is about 1065.5274353391.

The spelling of 1209745205 in words is "one billion, two hundred nine million, seven hundred forty-five thousand, two hundred five".