685083991 has 4 divisors (see below), whose sum is σ = 685489392. Its totient is φ = 684678592.

The previous prime is 685083983. The next prime is 685084009. The reversal of 685083991 is 199380586.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199380586 = 2 ⋅99690293.

It is a cyclic number.

It is not a de Polignac number, because 685083991 - 2³ = 685083983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685083941) 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, 200155 + ... + 203548.

It is an arithmetic number, because the mean of its divisors is an integer number (171372348).

Almost surely, 2^685083991 is an apocalyptic number.

685083991 is a deficient number, since it is larger than the sum of its proper divisors (405401).

685083991 is a wasteful number, since it uses less digits than its factorization.

685083991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405400.

The product of its (nonzero) digits is 466560, while the sum is 49.

The square root of 685083991 is about 26174.1091729977. The cubic root of 685083991 is about 881.5520093863.

The spelling of 685083991 in words is "six hundred eighty-five million, eighty-three thousand, nine hundred ninety-one".