67399721 has 2 divisors, whose sum is σ = 67399722. Its totient is φ = 67399720.

The previous prime is 67399711. The next prime is 67399723. The reversal of 67399721 is 12799376.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59892121 + 7507600 = 7739^2 + 2740^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-67399721 is a prime.

Together with 67399723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (67399723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33699860 + 33699861.

It is an arithmetic number, because the mean of its divisors is an integer number (33699861).

Almost surely, 2^67399721 is an apocalyptic number.

It is an amenable number.

67399721 is a deficient number, since it is larger than the sum of its proper divisors (1).

67399721 is an equidigital number, since it uses as much as digits as its factorization.

67399721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 142884, while the sum is 44.

The square root of 67399721 is about 8209.7333087013. The cubic root of 67399721 is about 406.9609136079.

The spelling of 67399721 in words is "sixty-seven million, three hundred ninety-nine thousand, seven hundred twenty-one".