168684521 has 2 divisors, whose sum is σ = 168684522. Its totient is φ = 168684520.

The previous prime is 168684511. The next prime is 168684533. The reversal of 168684521 is 125486861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 111091600 + 57592921 = 10540^2 + 7589^2 .

It is an emirp because it is prime and its reverse (125486861) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-168684521 is a prime.

It is not a weakly prime, because it can be changed into another prime (168684511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84342260 + 84342261.

It is an arithmetic number, because the mean of its divisors is an integer number (84342261).

Almost surely, 2^168684521 is an apocalyptic number.

It is an amenable number.

168684521 is a deficient number, since it is larger than the sum of its proper divisors (1).

168684521 is an equidigital number, since it uses as much as digits as its factorization.

168684521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 92160, while the sum is 41.

The square root of 168684521 is about 12987.8605243512. The cubic root of 168684521 is about 552.5332409721.

The spelling of 168684521 in words is "one hundred sixty-eight million, six hundred eighty-four thousand, five hundred twenty-one".