721281066881 has 4 divisors (see below), whose sum is σ = 722228874564. Its totient is φ = 720333259200.

The previous prime is 721281066871. The next prime is 721281066887. The reversal of 721281066881 is 188660182127.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 149162798656 + 572118268225 = 386216^2 + 756385^2 .

It is a cyclic number.

It is not a de Polignac number, because 721281066881 - 2⁶ = 721281066817 is a prime.

It is a super-2 number, since 2×721281066881² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721281066887) 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, 473902700 + ... + 473904221.

It is an arithmetic number, because the mean of its divisors is an integer number (180557218641).

Almost surely, 2^721281066881 is an apocalyptic number.

It is an amenable number.

721281066881 is a deficient number, since it is larger than the sum of its proper divisors (947807683).

721281066881 is an equidigital number, since it uses as much as digits as its factorization.

721281066881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947807682.

The product of its (nonzero) digits is 516096, while the sum is 50.

The spelling of 721281066881 in words is "seven hundred twenty-one billion, two hundred eighty-one million, sixty-six thousand, eight hundred eighty-one".