721111913 has 2 divisors, whose sum is σ = 721111914. Its totient is φ = 721111912.

The previous prime is 721111889. The next prime is 721112003. The reversal of 721111913 is 319111127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 367220569 + 353891344 = 19163^2 + 18812^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721111913 is a prime.

It is not a weakly prime, because it can be changed into another prime (721111513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360555956 + 360555957.

It is an arithmetic number, because the mean of its divisors is an integer number (360555957).

Almost surely, 2^721111913 is an apocalyptic number.

It is an amenable number.

721111913 is a deficient number, since it is larger than the sum of its proper divisors (1).

721111913 is an equidigital number, since it uses as much as digits as its factorization.

721111913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 378, while the sum is 26.

The square root of 721111913 is about 26853.5270122939. The cubic root of 721111913 is about 896.7420946177.

The spelling of 721111913 in words is "seven hundred twenty-one million, one hundred eleven thousand, nine hundred thirteen".