1297645861 has 4 divisors (see below), whose sum is σ = 1342392300. Its totient is φ = 1252899424.

The previous prime is 1297645847. The next prime is 1297645871. The reversal of 1297645861 is 1685467921.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1685467921 = 311 ⋅5419511.

It can be written as a sum of positive squares in 2 ways, for example, as 253128100 + 1044517761 = 15910^2 + 32319^2 .

It is a cyclic number.

It is not a de Polignac number, because 1297645861 - 2⁵ = 1297645829 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1297645841) 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, 22373176 + ... + 22373233.

It is an arithmetic number, because the mean of its divisors is an integer number (335598075).

Almost surely, 2^1297645861 is an apocalyptic number.

It is an amenable number.

1297645861 is a deficient number, since it is larger than the sum of its proper divisors (44746439).

1297645861 is an equidigital number, since it uses as much as digits as its factorization.

1297645861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44746438.

The product of its digits is 725760, while the sum is 49.

The square root of 1297645861 is about 36022.8519276306. The cubic root of 1297645861 is about 1090.7336925479.

The spelling of 1297645861 in words is "one billion, two hundred ninety-seven million, six hundred forty-five thousand, eight hundred sixty-one".