68421721 has 2 divisors, whose sum is σ = 68421722. Its totient is φ = 68421720.

The previous prime is 68421713. The next prime is 68421733. The reversal of 68421721 is 12712486.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61842496 + 6579225 = 7864^2 + 2565^2 .

It is a cyclic number.

It is not a de Polignac number, because 68421721 - 2³ = 68421713 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (68421761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34210860 + 34210861.

It is an arithmetic number, because the mean of its divisors is an integer number (34210861).

Almost surely, 2^68421721 is an apocalyptic number.

It is an amenable number.

68421721 is a deficient number, since it is larger than the sum of its proper divisors (1).

68421721 is an equidigital number, since it uses as much as digits as its factorization.

68421721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5376, while the sum is 31.

The square root of 68421721 is about 8271.7423194875. The cubic root of 68421721 is about 409.0075560084.

The spelling of 68421721 in words is "sixty-eight million, four hundred twenty-one thousand, seven hundred twenty-one".