72021020021 has 8 divisors (see below), whose sum is σ = 74507542200. Its totient is φ = 69534700480.

The previous prime is 72021020011. The next prime is 72021020033. The reversal of 72021020021 is 12002012027.

It can be written as a sum of positive squares in 4 ways, for example, as 18282825796 + 53738194225 = 135214^2 + 231815^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72021020021 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 (72021020011) 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 7 ways as a sum of consecutive naturals, for example, 1177175 + ... + 1236843.

It is an arithmetic number, because the mean of its divisors is an integer number (9313442775).

Almost surely, 2^72021020021 is an apocalyptic number.

It is an amenable number.

72021020021 is a deficient number, since it is larger than the sum of its proper divisors (2486522179).

72021020021 is a wasteful number, since it uses less digits than its factorization.

72021020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101319.

The product of its (nonzero) digits is 112, while the sum is 17.

Adding to 72021020021 its reverse (12002012027), we get a palindrome (84023032048).

The spelling of 72021020021 in words is "seventy-two billion, twenty-one million, twenty thousand, twenty-one".