686432221 has 2 divisors, whose sum is σ = 686432222. Its totient is φ = 686432220.

The previous prime is 686432191. The next prime is 686432231. The reversal of 686432221 is 122234686.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 628504900 + 57927321 = 25070^2 + 7611^2 .

It is a cyclic number.

It is not a de Polignac number, because 686432221 - 2⁷ = 686432093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686432231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343216110 + 343216111.

It is an arithmetic number, because the mean of its divisors is an integer number (343216111).

Almost surely, 2^686432221 is an apocalyptic number.

It is an amenable number.

686432221 is a deficient number, since it is larger than the sum of its proper divisors (1).

686432221 is an equidigital number, since it uses as much as digits as its factorization.

686432221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27648, while the sum is 34.

The square root of 686432221 is about 26199.8515453809. The cubic root of 686432221 is about 882.1299220035.

The spelling of 686432221 in words is "six hundred eighty-six million, four hundred thirty-two thousand, two hundred twenty-one".