8021560821 has 4 divisors (see below), whose sum is σ = 10695414432. Its totient is φ = 5347707212.

The previous prime is 8021560819. The next prime is 8021560949. The reversal of 8021560821 is 1280651208.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 8021560821 - 2¹ = 8021560819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8021564821) 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, 1336926801 + ... + 1336926806.

It is an arithmetic number, because the mean of its divisors is an integer number (2673853608).

Almost surely, 2^8021560821 is an apocalyptic number.

It is an amenable number.

8021560821 is a deficient number, since it is larger than the sum of its proper divisors (2673853611).

8021560821 is a wasteful number, since it uses less digits than its factorization.

8021560821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2673853610.

The product of its (nonzero) digits is 7680, while the sum is 33.

The square root of 8021560821 is about 89563.1666534854. The cubic root of 8021560821 is about 2001.7951233673.

The spelling of 8021560821 in words is "eight billion, twenty-one million, five hundred sixty thousand, eight hundred twenty-one".