721101613 has 2 divisors, whose sum is σ = 721101614. Its totient is φ = 721101612.

The previous prime is 721101611. The next prime is 721101649. The reversal of 721101613 is 316101127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 436099689 + 285001924 = 20883^2 + 16882^2 .

It is a cyclic number.

It is not a de Polignac number, because 721101613 - 2¹ = 721101611 is a prime.

Together with 721101611, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721101611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360550806 + 360550807.

It is an arithmetic number, because the mean of its divisors is an integer number (360550807).

Almost surely, 2^721101613 is an apocalyptic number.

It is an amenable number.

721101613 is a deficient number, since it is larger than the sum of its proper divisors (1).

721101613 is an equidigital number, since it uses as much as digits as its factorization.

721101613 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 721101613 is about 26853.3352304700. The cubic root of 721101613 is about 896.7378250596.

The spelling of 721101613 in words is "seven hundred twenty-one million, one hundred one thousand, six hundred thirteen".