721938666731 has 2 divisors, whose sum is σ = 721938666732. Its totient is φ = 721938666730.

The previous prime is 721938666671. The next prime is 721938666733. The reversal of 721938666731 is 137666839127.

It is a strong prime.

It is an emirp because it is prime and its reverse (137666839127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721938666731 - 2⁶ = 721938666667 is a prime.

It is a super-2 number, since 2×721938666731² (a number of 25 digits) contains 22 as substring.

Together with 721938666733, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (721938666733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360969333365 + 360969333366.

It is an arithmetic number, because the mean of its divisors is an integer number (360969333366).

Almost surely, 2^721938666731 is an apocalyptic number.

721938666731 is a deficient number, since it is larger than the sum of its proper divisors (1).

721938666731 is an equidigital number, since it uses as much as digits as its factorization.

721938666731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13716864, while the sum is 59.

The spelling of 721938666731 in words is "seven hundred twenty-one billion, nine hundred thirty-eight million, six hundred sixty-six thousand, seven hundred thirty-one".