67616821 has 2 divisors, whose sum is σ = 67616822. Its totient is φ = 67616820.

The previous prime is 67616819. The next prime is 67616851. The reversal of 67616821 is 12861676.

67616821 = 5814² + 5815².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 33814225 + 33802596 = 5815^2 + 5814^2 .

It is a cyclic number.

It is not a de Polignac number, because 67616821 - 2¹ = 67616819 is a prime.

Together with 67616819, 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 (67616851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33808410 + 33808411.

It is an arithmetic number, because the mean of its divisors is an integer number (33808411).

Almost surely, 2^67616821 is an apocalyptic number.

67616821 is the 5815-th centered square number.

It is an amenable number.

67616821 is a deficient number, since it is larger than the sum of its proper divisors (1).

67616821 is an equidigital number, since it uses as much as digits as its factorization.

67616821 is an evil number, because the sum of its binary digits is even.

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

The square root of 67616821 is about 8222.9447888211. The cubic root of 67616821 is about 407.3973967281.

The spelling of 67616821 in words is "sixty-seven million, six hundred sixteen thousand, eight hundred twenty-one".