1261312513 has 4 divisors (see below), whose sum is σ = 1269665728. Its totient is φ = 1252959300.

The previous prime is 1261312489. The next prime is 1261312523. The reversal of 1261312513 is 3152131621.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1261312513 - 2¹³ = 1261304321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261312523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4176381 + ... + 4176682.

It is an arithmetic number, because the mean of its divisors is an integer number (317416432).

Almost surely, 2^1261312513 is an apocalyptic number.

It is an amenable number.

1261312513 is a deficient number, since it is larger than the sum of its proper divisors (8353215).

1261312513 is an equidigital number, since it uses as much as digits as its factorization.

1261312513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8353214.

The product of its digits is 1080, while the sum is 25.

The square root of 1261312513 is about 35514.9618189292. The cubic root of 1261312513 is about 1080.4572004001.

The spelling of 1261312513 in words is "one billion, two hundred sixty-one million, three hundred twelve thousand, five hundred thirteen".