1685016851821 has 2 divisors, whose sum is σ = 1685016851822. Its totient is φ = 1685016851820.

The previous prime is 1685016851803. The next prime is 1685016851839. The reversal of 1685016851821 is 1281586105861.

It is a balanced prime because it is at equal distance from previous prime (1685016851803) and next prime (1685016851839).

It can be written as a sum of positive squares in only one way, i.e., 959008904100 + 726007947721 = 979290^2 + 852061^2 .

It is a cyclic number.

It is not a de Polignac number, because 1685016851821 - 2¹⁷ = 1685016720749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1685016852821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842508425910 + 842508425911.

It is an arithmetic number, because the mean of its divisors is an integer number (842508425911).

Almost surely, 2^{1685016851821} is an apocalyptic number.

It is an amenable number.

1685016851821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685016851821 is an equidigital number, since it uses as much as digits as its factorization.

1685016851821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 921600, while the sum is 52.

The spelling of 1685016851821 in words is "one trillion, six hundred eighty-five billion, sixteen million, eight hundred fifty-one thousand, eight hundred twenty-one".