68721520421 has 2 divisors, whose sum is σ = 68721520422. Its totient is φ = 68721520420.

The previous prime is 68721520411. The next prime is 68721520459. The reversal of 68721520421 is 12402512786.

It is an a-pointer prime, because the next prime (68721520459) can be obtained adding 68721520421 to its sum of digits (38).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59457457921 + 9264062500 = 243839^2 + 96250^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-68721520421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (68721520411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34360760210 + 34360760211.

It is an arithmetic number, because the mean of its divisors is an integer number (34360760211).

Almost surely, 2^68721520421 is an apocalyptic number.

It is an amenable number.

68721520421 is a deficient number, since it is larger than the sum of its proper divisors (1).

68721520421 is an equidigital number, since it uses as much as digits as its factorization.

68721520421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 53760, while the sum is 38.

The spelling of 68721520421 in words is "sixty-eight billion, seven hundred twenty-one million, five hundred twenty thousand, four hundred twenty-one".