686432921 has 2 divisors, whose sum is σ = 686432922. Its totient is φ = 686432920.

The previous prime is 686432909. The next prime is 686432993. The reversal of 686432921 is 129234686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 611869696 + 74563225 = 24736^2 + 8635^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-686432921 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (686432221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343216460 + 343216461.

It is an arithmetic number, because the mean of its divisors is an integer number (343216461).

Almost surely, 2^686432921 is an apocalyptic number.

It is an amenable number.

686432921 is a deficient number, since it is larger than the sum of its proper divisors (1).

686432921 is an equidigital number, since it uses as much as digits as its factorization.

686432921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 41.

The square root of 686432921 is about 26199.8649042319. The cubic root of 686432921 is about 882.1302218587.

The spelling of 686432921 in words is "six hundred eighty-six million, four hundred thirty-two thousand, nine hundred twenty-one".