1291893857 has 8 divisors (see below), whose sum is σ = 1304288136. Its totient is φ = 1279516672.

The previous prime is 1291893851. The next prime is 1291893917. The reversal of 1291893857 is 7583981921.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 166693921 + 1125199936 = 12911^2 + 33544^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1291893857 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1291893799 and 1291893808.

It is not an unprimeable number, because it can be changed into a prime (1291893851) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 188393 + ... + 195129.

It is an arithmetic number, because the mean of its divisors is an integer number (163036017).

Almost surely, 2^1291893857 is an apocalyptic number.

It is an amenable number.

1291893857 is a deficient number, since it is larger than the sum of its proper divisors (12394279).

1291893857 is a wasteful number, since it uses less digits than its factorization.

1291893857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8547.

The product of its digits is 1088640, while the sum is 53.

The square root of 1291893857 is about 35942.9249922707. The cubic root of 1291893857 is about 1089.1196935247.

The spelling of 1291893857 in words is "one billion, two hundred ninety-one million, eight hundred ninety-three thousand, eight hundred fifty-seven".