1021316665 has 4 divisors (see below), whose sum is σ = 1225580004. Its totient is φ = 817053328.

The previous prime is 1021316651. The next prime is 1021316687. The reversal of 1021316665 is 5666131201.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5666131201 = 47 ⋅120555983.

It can be written as a sum of positive squares in 2 ways, for example, as 210946576 + 810370089 = 14524^2 + 28467^2 .

It is a cyclic number.

It is not a de Polignac number, because 1021316665 - 2¹¹ = 1021314617 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102131662 + ... + 102131671.

It is an arithmetic number, because the mean of its divisors is an integer number (306395001).

Almost surely, 2^1021316665 is an apocalyptic number.

It is an amenable number.

1021316665 is a deficient number, since it is larger than the sum of its proper divisors (204263339).

1021316665 is an equidigital number, since it uses as much as digits as its factorization.

1021316665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204263338.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 1021316665 is about 31958.0453876641. The cubic root of 1021316665 is about 1007.0556556413.

Adding to 1021316665 its reverse (5666131201), we get a palindrome (6687447866).

The spelling of 1021316665 in words is "one billion, twenty-one million, three hundred sixteen thousand, six hundred sixty-five".