67716721 has 2 divisors, whose sum is σ = 67716722. Its totient is φ = 67716720.

The previous prime is 67716689. The next prime is 67716749. The reversal of 67716721 is 12761776.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49773025 + 17943696 = 7055^2 + 4236^2 .

It is a cyclic number.

It is not a de Polignac number, because 67716721 - 2⁵ = 67716689 is a prime.

It is a Chen prime.

It is equal to p_3991609 and since 67716721 and 3991609 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (67716221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33858360 + 33858361.

It is an arithmetic number, because the mean of its divisors is an integer number (33858361).

Almost surely, 2^67716721 is an apocalyptic number.

It is an amenable number.

67716721 is a deficient number, since it is larger than the sum of its proper divisors (1).

67716721 is an equidigital number, since it uses as much as digits as its factorization.

67716721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24696, while the sum is 37.

The square root of 67716721 is about 8229.0170129852. The cubic root of 67716721 is about 407.5979334796.

The spelling of 67716721 in words is "sixty-seven million, seven hundred sixteen thousand, seven hundred twenty-one".