857640749 has 4 divisors (see below), whose sum is σ = 980160864. Its totient is φ = 735120636.

The previous prime is 857640673. The next prime is 857640811. The reversal of 857640749 is 947046758.

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 857640749 - 2⁸ = 857640493 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 857640697 and 857640706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (857600749) 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, 61260047 + ... + 61260060.

It is an arithmetic number, because the mean of its divisors is an integer number (245040216).

Almost surely, 2^857640749 is an apocalyptic number.

It is an amenable number.

857640749 is a deficient number, since it is larger than the sum of its proper divisors (122520115).

857640749 is a wasteful number, since it uses less digits than its factorization.

857640749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122520114.

The product of its (nonzero) digits is 1693440, while the sum is 50.

The square root of 857640749 is about 29285.5040762491. The cubic root of 857640749 is about 950.0981427693.

The spelling of 857640749 in words is "eight hundred fifty-seven million, six hundred forty thousand, seven hundred forty-nine".