8021571665 has 8 divisors (see below), whose sum is σ = 9629267688. Its totient is φ = 6415002880.

The previous prime is 8021571659. The next prime is 8021571707. The reversal of 8021571665 is 5661751208.

It can be written as a sum of positive squares in 4 ways, for example, as 10784656 + 8010787009 = 3284^2 + 89503^2 .

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

It is not a de Polignac number, because 8021571665 - 2¹⁸ = 8021309521 is a prime.

It is a super-2 number, since 2×8021571665² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 266072 + ... + 294681.

It is an arithmetic number, because the mean of its divisors is an integer number (1203658461).

Almost surely, 2^8021571665 is an apocalyptic number.

It is an amenable number.

8021571665 is a deficient number, since it is larger than the sum of its proper divisors (1607696023).

8021571665 is a wasteful number, since it uses less digits than its factorization.

8021571665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563619.

The product of its (nonzero) digits is 100800, while the sum is 41.

The square root of 8021571665 is about 89563.2271917443. The cubic root of 8021571665 is about 2001.7960254136.

The spelling of 8021571665 in words is "eight billion, twenty-one million, five hundred seventy-one thousand, six hundred sixty-five".