78143707816721 has 2 divisors, whose sum is σ = 78143707816722. Its totient is φ = 78143707816720.

The previous prime is 78143707816651. The next prime is 78143707816841. The reversal of 78143707816721 is 12761870734187.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62530454064400 + 15613253752321 = 7907620^2 + 3951361^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78143707816721 is a prime.

It is a super-2 number, since 2×78143707816721² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78143707812721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39071853908360 + 39071853908361.

It is an arithmetic number, because the mean of its divisors is an integer number (39071853908361).

Almost surely, 2^{78143707816721} is an apocalyptic number.

It is an amenable number.

78143707816721 is a deficient number, since it is larger than the sum of its proper divisors (1).

78143707816721 is an equidigital number, since it uses as much as digits as its factorization.

78143707816721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 22127616, while the sum is 62.

The spelling of 78143707816721 in words is "seventy-eight trillion, one hundred forty-three billion, seven hundred seven million, eight hundred sixteen thousand, seven hundred twenty-one".