1685355385221 has 8 divisors (see below), whose sum is σ = 2496822792960. Its totient is φ = 1123570256796.

The previous prime is 1685355385213. The next prime is 1685355385243. The reversal of 1685355385221 is 1225835535861.

1685355385221 is a `hidden beast` number, since 1 + 6 + 8 + 5 + 3 + 553 + 85 + 2 + 2 + 1 = 666.

It is not a de Polignac number, because 1685355385221 - 2³ = 1685355385213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1685355385211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31210284885 + ... + 31210284938.

It is an arithmetic number, because the mean of its divisors is an integer number (312102849120).

Almost surely, 2^{1685355385221} is an apocalyptic number.

It is an amenable number.

1685355385221 is a deficient number, since it is larger than the sum of its proper divisors (811467407739).

1685355385221 is an equidigital number, since it uses as much as digits as its factorization.

1685355385221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62420569832 (or 62420569826 counting only the distinct ones).

The product of its digits is 8640000, while the sum is 54.

The spelling of 1685355385221 in words is "one trillion, six hundred eighty-five billion, three hundred fifty-five million, three hundred eighty-five thousand, two hundred twenty-one".