684869857 has 4 divisors (see below), whose sum is σ = 782708416. Its totient is φ = 587031300.

The previous prime is 684869851. The next prime is 684869879. The reversal of 684869857 is 758968486.

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, and also an emirpimes, since its reverse is a distinct semiprime: 758968486 = 2 ⋅379484243.

It is a cyclic number.

It is not a de Polignac number, because 684869857 - 2¹⁹ = 684345569 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 684869795 and 684869804.

It is not an unprimeable number, because it can be changed into a prime (684869851) 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, 48919269 + ... + 48919282.

It is an arithmetic number, because the mean of its divisors is an integer number (195677104).

Almost surely, 2^684869857 is an apocalyptic number.

It is an amenable number.

684869857 is a deficient number, since it is larger than the sum of its proper divisors (97838559).

684869857 is an equidigital number, since it uses as much as digits as its factorization.

684869857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97838558.

The product of its digits is 23224320, while the sum is 61.

The square root of 684869857 is about 26170.0182842886. The cubic root of 684869857 is about 881.4601520707.

The spelling of 684869857 in words is "six hundred eighty-four million, eight hundred sixty-nine thousand, eight hundred fifty-seven".