685566971 has 4 divisors (see below), whose sum is σ = 685732200. Its totient is φ = 685401744.

The previous prime is 685566943. The next prime is 685567009. The reversal of 685566971 is 179665586.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 179665586 = 2 ⋅89832793.

It is a cyclic number.

It is not a de Polignac number, because 685566971 - 2⁶ = 685566907 is a prime.

It is a super-2 number, since 2×685566971² = 940004143452229682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685566901) 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, 76226 + ... + 84743.

It is an arithmetic number, because the mean of its divisors is an integer number (171433050).

Almost surely, 2^685566971 is an apocalyptic number.

685566971 is a deficient number, since it is larger than the sum of its proper divisors (165229).

685566971 is a wasteful number, since it uses less digits than its factorization.

685566971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165228.

The product of its digits is 2721600, while the sum is 53.

The square root of 685566971 is about 26183.3338404413. Note that the first 3 decimals coincide. The cubic root of 685566971 is about 881.7591236373.

The spelling of 685566971 in words is "six hundred eighty-five million, five hundred sixty-six thousand, nine hundred seventy-one".