686221823 has 6 divisors (see below), whose sum is σ = 798258096. Its totient is φ = 588190092.

The previous prime is 686221807. The next prime is 686221831. The reversal of 686221823 is 328122686.

It is not a de Polignac number, because 686221823 - 2⁴ = 686221807 is a prime.

It is a super-2 number, since 2×686221823² = 941800780722886658, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686221873) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7002215 + ... + 7002312.

It is an arithmetic number, because the mean of its divisors is an integer number (133043016).

Almost surely, 2^686221823 is an apocalyptic number.

686221823 is a deficient number, since it is larger than the sum of its proper divisors (112036273).

686221823 is a wasteful number, since it uses less digits than its factorization.

686221823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14004541 (or 14004534 counting only the distinct ones).

The product of its digits is 55296, while the sum is 38.

The square root of 686221823 is about 26195.8359858967. The cubic root of 686221823 is about 882.0397857252.

The spelling of 686221823 in words is "six hundred eighty-six million, two hundred twenty-one thousand, eight hundred twenty-three".