67166821 has 2 divisors, whose sum is σ = 67166822. Its totient is φ = 67166820.

The previous prime is 67166819. The next prime is 67166833. The reversal of 67166821 is 12866176.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65448100 + 1718721 = 8090^2 + 1311^2 .

It is a cyclic number.

It is not a de Polignac number, because 67166821 - 2¹ = 67166819 is a prime.

It is a super-2 number, since 2×67166821² = 9022763686492082, which contains 22 as substring.

Together with 67166819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (67166221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33583410 + 33583411.

It is an arithmetic number, because the mean of its divisors is an integer number (33583411).

Almost surely, 2^67166821 is an apocalyptic number.

It is an amenable number.

67166821 is a deficient number, since it is larger than the sum of its proper divisors (1).

67166821 is an equidigital number, since it uses as much as digits as its factorization.

67166821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 37.

The square root of 67166821 is about 8195.5366511291. The cubic root of 67166821 is about 406.4916209674.

The spelling of 67166821 in words is "sixty-seven million, one hundred sixty-six thousand, eight hundred twenty-one".