686974821 has 32 divisors (see below), whose sum is σ = 998245248. Its totient is φ = 417726720.

The previous prime is 686974807. The next prime is 686974829. The reversal of 686974821 is 128479686.

It is not a de Polignac number, because 686974821 - 2⁷ = 686974693 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (686974829) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2166955 + ... + 2167271.

It is an arithmetic number, because the mean of its divisors is an integer number (31195164).

Almost surely, 2^686974821 is an apocalyptic number.

It is an amenable number.

686974821 is a deficient number, since it is larger than the sum of its proper divisors (311270427).

686974821 is a wasteful number, since it uses less digits than its factorization.

686974821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821.

The product of its digits is 1161216, while the sum is 51.

The square root of 686974821 is about 26210.2045203772. The cubic root of 686974821 is about 882.3622914541.

The spelling of 686974821 in words is "six hundred eighty-six million, nine hundred seventy-four thousand, eight hundred twenty-one".