721161445 has 8 divisors (see below), whose sum is σ = 870906744. Its totient is φ = 573253824.

The previous prime is 721161439. The next prime is 721161449. The reversal of 721161445 is 544161127.

It can be written as a sum of positive squares in 4 ways, for example, as 1258884 + 719902561 = 1122^2 + 26831^2 .

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 721161445 - 2¹⁵ = 721128677 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 (721161449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 458554 + ... + 460123.

It is an arithmetic number, because the mean of its divisors is an integer number (108863343).

Almost surely, 2^721161445 is an apocalyptic number.

It is an amenable number.

721161445 is a deficient number, since it is larger than the sum of its proper divisors (149745299).

721161445 is a wasteful number, since it uses less digits than its factorization.

721161445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 918839.

The product of its digits is 6720, while the sum is 31.

The square root of 721161445 is about 26854.4492589217. The cubic root of 721161445 is about 896.7626260644.

The spelling of 721161445 in words is "seven hundred twenty-one million, one hundred sixty-one thousand, four hundred forty-five".