721020110021 has 8 divisors (see below), whose sum is σ = 722094739800. Its totient is φ = 719946220032.

The previous prime is 721020110003. The next prime is 721020110081. The reversal of 721020110021 is 120011020127.

It can be written as a sum of positive squares in 4 ways, for example, as 240894456100 + 480125653921 = 490810^2 + 692911^2 .

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 721020110021 - 2³⁴ = 703840240837 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 (721020110081) 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, 1781291 + ... + 2148263.

It is an arithmetic number, because the mean of its divisors is an integer number (90261842475).

Almost surely, 2^721020110021 is an apocalyptic number.

It is an amenable number.

721020110021 is a deficient number, since it is larger than the sum of its proper divisors (1074629779).

721020110021 is a wasteful number, since it uses less digits than its factorization.

721020110021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369895.

The product of its (nonzero) digits is 56, while the sum is 17.

Adding to 721020110021 its reverse (120011020127), we get a palindrome (841031130148).

The spelling of 721020110021 in words is "seven hundred twenty-one billion, twenty million, one hundred ten thousand, twenty-one".