721643715887 has 2 divisors, whose sum is σ = 721643715888. Its totient is φ = 721643715886.

The previous prime is 721643715853. The next prime is 721643715893. The reversal of 721643715887 is 788517346127.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721643715887 - 2¹⁰ = 721643714863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721643715817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360821857943 + 360821857944.

It is an arithmetic number, because the mean of its divisors is an integer number (360821857944).

Almost surely, 2^721643715887 is an apocalyptic number.

721643715887 is a deficient number, since it is larger than the sum of its proper divisors (1).

721643715887 is an equidigital number, since it uses as much as digits as its factorization.

721643715887 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15805440, while the sum is 59.

The spelling of 721643715887 in words is "seven hundred twenty-one billion, six hundred forty-three million, seven hundred fifteen thousand, eight hundred eighty-seven".