721334621 has 4 divisors (see below), whose sum is σ = 824382432. Its totient is φ = 618286812.

The previous prime is 721334597. The next prime is 721334651. The reversal of 721334621 is 126433127.

It is a happy number.

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 721334621 - 2¹⁰ = 721333597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721334651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51523895 + ... + 51523908.

It is an arithmetic number, because the mean of its divisors is an integer number (206095608).

Almost surely, 2^721334621 is an apocalyptic number.

It is an amenable number.

721334621 is a deficient number, since it is larger than the sum of its proper divisors (103047811).

721334621 is a wasteful number, since it uses less digits than its factorization.

721334621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103047810.

The product of its digits is 6048, while the sum is 29.

The square root of 721334621 is about 26857.6734100331. The cubic root of 721334621 is about 896.8344016409.

Adding to 721334621 its reverse (126433127), we get a palindrome (847767748).

The spelling of 721334621 in words is "seven hundred twenty-one million, three hundred thirty-four thousand, six hundred twenty-one".