721816417 has 4 divisors (see below), whose sum is σ = 824933056. Its totient is φ = 618699780.

The previous prime is 721816411. The next prime is 721816451. The reversal of 721816417 is 714618127.

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 721816417 - 2¹¹ = 721814369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721816411) 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, 51558309 + ... + 51558322.

It is an arithmetic number, because the mean of its divisors is an integer number (206233264).

Almost surely, 2^721816417 is an apocalyptic number.

It is an amenable number.

721816417 is a deficient number, since it is larger than the sum of its proper divisors (103116639).

721816417 is a wasteful number, since it uses less digits than its factorization.

721816417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103116638.

The product of its digits is 18816, while the sum is 37.

The square root of 721816417 is about 26866.6413420063. The cubic root of 721816417 is about 897.0340293168.

The spelling of 721816417 in words is "seven hundred twenty-one million, eight hundred sixteen thousand, four hundred seventeen".