1684127821 has 2 divisors, whose sum is σ = 1684127822. Its totient is φ = 1684127820.

The previous prime is 1684127813. The next prime is 1684127857. The reversal of 1684127821 is 1287214861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1422044100 + 262083721 = 37710^2 + 16189^2 .

It is a cyclic number.

It is not a de Polignac number, because 1684127821 - 2³ = 1684127813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1684157821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842063910 + 842063911.

It is an arithmetic number, because the mean of its divisors is an integer number (842063911).

Almost surely, 2^1684127821 is an apocalyptic number.

It is an amenable number.

1684127821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1684127821 is an equidigital number, since it uses as much as digits as its factorization.

1684127821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43008, while the sum is 40.

The square root of 1684127821 is about 41038.1264314052. The cubic root of 1684127821 is about 1189.7572230295.

The spelling of 1684127821 in words is "one billion, six hundred eighty-four million, one hundred twenty-seven thousand, eight hundred twenty-one".