684949834021 has 2 divisors, whose sum is σ = 684949834022. Its totient is φ = 684949834020.

The previous prime is 684949834013. The next prime is 684949834043. The reversal of 684949834021 is 120438949486.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 598975384225 + 85974449796 = 773935^2 + 293214^2 .

It is a cyclic number.

It is not a de Polignac number, because 684949834021 - 2³ = 684949834013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (684949834061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342474917010 + 342474917011.

It is an arithmetic number, because the mean of its divisors is an integer number (342474917011).

Almost surely, 2^684949834021 is an apocalyptic number.

It is an amenable number.

684949834021 is a deficient number, since it is larger than the sum of its proper divisors (1).

684949834021 is an equidigital number, since it uses as much as digits as its factorization.

684949834021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11943936, while the sum is 58.

The spelling of 684949834021 in words is "six hundred eighty-four billion, nine hundred forty-nine million, eight hundred thirty-four thousand, twenty-one".