8021556720073 has 4 divisors (see below), whose sum is σ = 8638599544708. Its totient is φ = 7404513895440.

The previous prime is 8021556720049. The next prime is 8021556720103. The reversal of 8021556720073 is 3700276551208.

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 5440145737744 + 2581410982329 = 2332412^2 + 1606677^2 .

It is a cyclic number.

It is not a de Polignac number, because 8021556720073 - 2⁵ = 8021556720041 is a prime.

It is a super-2 number, since 2×8021556720073² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8021556720013) 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, 308521412298 + ... + 308521412323.

It is an arithmetic number, because the mean of its divisors is an integer number (2159649886177).

Almost surely, 2^{8021556720073} is an apocalyptic number.

It is an amenable number.

8021556720073 is a deficient number, since it is larger than the sum of its proper divisors (617042824635).

8021556720073 is a wasteful number, since it uses less digits than its factorization.

8021556720073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 617042824634.

The product of its (nonzero) digits is 705600, while the sum is 46.

The spelling of 8021556720073 in words is "eight trillion, twenty-one billion, five hundred fifty-six million, seven hundred twenty thousand, seventy-three".