67981621 has 2 divisors, whose sum is σ = 67981622. Its totient is φ = 67981620.

The previous prime is 67981619. The next prime is 67981631. The reversal of 67981621 is 12618976.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45037521 + 22944100 = 6711^2 + 4790^2 .

It is a cyclic number.

It is not a de Polignac number, because 67981621 - 2¹ = 67981619 is a prime.

Together with 67981619, 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 (67981631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33990810 + 33990811.

It is an arithmetic number, because the mean of its divisors is an integer number (33990811).

Almost surely, 2^67981621 is an apocalyptic number.

It is an amenable number.

67981621 is a deficient number, since it is larger than the sum of its proper divisors (1).

67981621 is an equidigital number, since it uses as much as digits as its factorization.

67981621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 40.

The square root of 67981621 is about 8245.0967853628. The cubic root of 67981621 is about 408.1287339669.

The spelling of 67981621 in words is "sixty-seven million, nine hundred eighty-one thousand, six hundred twenty-one".