721521365 has 8 divisors (see below), whose sum is σ = 870221880. Its totient is φ = 574286272.

The previous prime is 721521347. The next prime is 721521377. The reversal of 721521365 is 563125127.

It can be written as a sum of positive squares in 4 ways, for example, as 480091921 + 241429444 = 21911^2 + 15538^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721521365 - 2¹⁴ = 721504981 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 365270 + ... + 367239.

It is an arithmetic number, because the mean of its divisors is an integer number (108777735).

Almost surely, 2^721521365 is an apocalyptic number.

It is an amenable number.

721521365 is a deficient number, since it is larger than the sum of its proper divisors (148700515).

721521365 is a wasteful number, since it uses less digits than its factorization.

721521365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 732711.

The product of its digits is 12600, while the sum is 32.

The square root of 721521365 is about 26861.1497333975. The cubic root of 721521365 is about 896.9117878212.

The spelling of 721521365 in words is "seven hundred twenty-one million, five hundred twenty-one thousand, three hundred sixty-five".