13166665021 has 4 divisors (see below), whose sum is σ = 13167074844. Its totient is φ = 13166255200.

The previous prime is 13166664961. The next prime is 13166665033. The reversal of 13166665021 is 12056666131.

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 3560508900 + 9606156121 = 59670^2 + 98011^2 .

It is a cyclic number.

It is not a de Polignac number, because 13166665021 - 2¹⁵ = 13166632253 is a prime.

It is a super-2 number, since 2×13166665021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13166665921) 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, 152200 + ... + 222481.

It is an arithmetic number, because the mean of its divisors is an integer number (3291768711).

Almost surely, 2^13166665021 is an apocalyptic number.

It is an amenable number.

13166665021 is a deficient number, since it is larger than the sum of its proper divisors (409823).

13166665021 is an equidigital number, since it uses as much as digits as its factorization.

13166665021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 409822.

The product of its (nonzero) digits is 38880, while the sum is 37.

The spelling of 13166665021 in words is "thirteen billion, one hundred sixty-six million, six hundred sixty-five thousand, twenty-one".