721918265 has 4 divisors (see below), whose sum is σ = 866301924. Its totient is φ = 577534608.

The previous prime is 721918229. The next prime is 721918279. The reversal of 721918265 is 562819127.

721918265 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 544708921 + 177209344 = 23339^2 + 13312^2 .

It is a cyclic number.

It is not a de Polignac number, because 721918265 - 2¹⁸ = 721656121 is a prime.

It is a super-2 number, since 2×721918265² = 1042331962681220450, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72191822 + ... + 72191831.

It is an arithmetic number, because the mean of its divisors is an integer number (216575481).

Almost surely, 2^721918265 is an apocalyptic number.

It is an amenable number.

721918265 is a deficient number, since it is larger than the sum of its proper divisors (144383659).

721918265 is a wasteful number, since it uses less digits than its factorization.

721918265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144383658.

The product of its digits is 60480, while the sum is 41.

The square root of 721918265 is about 26868.5367111795. The cubic root of 721918265 is about 897.0762177104.

The spelling of 721918265 in words is "seven hundred twenty-one million, nine hundred eighteen thousand, two hundred sixty-five".