721622521 has 4 divisors (see below), whose sum is σ = 721810944. Its totient is φ = 721434100.

The previous prime is 721622491. The next prime is 721622543. The reversal of 721622521 is 125226127.

721622521 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 721622521 - 2¹³ = 721614329 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721622521.

It is not an unprimeable number, because it can be changed into a prime (721622621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 88345 + ... + 96166.

It is an arithmetic number, because the mean of its divisors is an integer number (180452736).

Almost surely, 2^721622521 is an apocalyptic number.

It is an amenable number.

721622521 is a deficient number, since it is larger than the sum of its proper divisors (188423).

721622521 is a wasteful number, since it uses less digits than its factorization.

721622521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188422.

The product of its digits is 3360, while the sum is 28.

The square root of 721622521 is about 26863.0326098897. The cubic root of 721622521 is about 896.9537010033.

Adding to 721622521 its reverse (125226127), we get a palindrome (846848648).

The spelling of 721622521 in words is "seven hundred twenty-one million, six hundred twenty-two thousand, five hundred twenty-one".