857397491 has 4 divisors (see below), whose sum is σ = 869473584. Its totient is φ = 845321400.

The previous prime is 857397487. The next prime is 857397493. The reversal of 857397491 is 194793758.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 194793758 = 2 ⋅97396879.

It is a cyclic number.

It is not a de Polignac number, because 857397491 - 2² = 857397487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (857397493) 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, 6037940 + ... + 6038081.

It is an arithmetic number, because the mean of its divisors is an integer number (217368396).

Almost surely, 2^857397491 is an apocalyptic number.

857397491 is a deficient number, since it is larger than the sum of its proper divisors (12076093).

857397491 is a wasteful number, since it uses less digits than its factorization.

857397491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12076092.

The product of its digits is 1905120, while the sum is 53.

The square root of 857397491 is about 29281.3505665295. The cubic root of 857397491 is about 950.0083068526.

The spelling of 857397491 in words is "eight hundred fifty-seven million, three hundred ninety-seven thousand, four hundred ninety-one".