1261604345 has 4 divisors (see below), whose sum is σ = 1513925220. Its totient is φ = 1009283472.

The previous prime is 1261604329. The next prime is 1261604347. The reversal of 1261604345 is 5434061621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5434061621 = 28729 ⋅189149.

It can be written as a sum of positive squares in 2 ways, for example, as 438316096 + 823288249 = 20936^2 + 28693^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261604345 - 2⁴ = 1261604329 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1261604347) 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 in 3 ways as a sum of consecutive naturals, for example, 126160430 + ... + 126160439.

It is an arithmetic number, because the mean of its divisors is an integer number (378481305).

Almost surely, 2^1261604345 is an apocalyptic number.

It is an amenable number.

1261604345 is a deficient number, since it is larger than the sum of its proper divisors (252320875).

1261604345 is an equidigital number, since it uses as much as digits as its factorization.

1261604345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252320874.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 1261604345 is about 35519.0701595636. The cubic root of 1261604345 is about 1080.5405230415.

Adding to 1261604345 its reverse (5434061621), we get a palindrome (6695665966).

The spelling of 1261604345 in words is "one billion, two hundred sixty-one million, six hundred four thousand, three hundred forty-five".