71998861309 has 2 divisors, whose sum is σ = 71998861310. Its totient is φ = 71998861308.

The previous prime is 71998861189. The next prime is 71998861321. The reversal of 71998861309 is 90316889917.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70272708100 + 1726153209 = 265090^2 + 41547^2 .

It is an emirp because it is prime and its reverse (90316889917) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71998861309 - 2⁹ = 71998860797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71998861339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35999430654 + 35999430655.

It is an arithmetic number, because the mean of its divisors is an integer number (35999430655).

Almost surely, 2^71998861309 is an apocalyptic number.

It is an amenable number.

71998861309 is a deficient number, since it is larger than the sum of its proper divisors (1).

71998861309 is an equidigital number, since it uses as much as digits as its factorization.

71998861309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5878656, while the sum is 61.

The spelling of 71998861309 in words is "seventy-one billion, nine hundred ninety-eight million, eight hundred sixty-one thousand, three hundred nine".