721344581 has 4 divisors (see below), whose sum is σ = 733169964. Its totient is φ = 709519200.

The previous prime is 721344577. The next prime is 721344599. The reversal of 721344581 is 185443127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 185443127 = 1033 ⋅179519.

It can be written as a sum of positive squares in 2 ways, for example, as 53949025 + 667395556 = 7345^2 + 25834^2 .

It is a cyclic number.

It is not a de Polignac number, because 721344581 - 2² = 721344577 is a prime.

It is a super-2 number, since 2×721344581² = 1040676009076131122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721344541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5912600 + ... + 5912721.

It is an arithmetic number, because the mean of its divisors is an integer number (183292491).

Almost surely, 2^721344581 is an apocalyptic number.

It is an amenable number.

721344581 is a deficient number, since it is larger than the sum of its proper divisors (11825383).

721344581 is a wasteful number, since it uses less digits than its factorization.

721344581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11825382.

The product of its digits is 26880, while the sum is 35.

The square root of 721344581 is about 26857.8588312620. The cubic root of 721344581 is about 896.8385293736.

The spelling of 721344581 in words is "seven hundred twenty-one million, three hundred forty-four thousand, five hundred eighty-one".