16664253121 has 4 divisors (see below), whose sum is σ = 16665314692. Its totient is φ = 16663191552.

The previous prime is 16664253101. The next prime is 16664253167. The reversal of 16664253121 is 12135246661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12135246661 = 199 ⋅60981139.

It can be written as a sum of positive squares in 2 ways, for example, as 5630851521 + 11033401600 = 75039^2 + 105040^2 .

It is a cyclic number.

It is not a de Polignac number, because 16664253121 - 2¹⁹ = 16663728833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16664253101) 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, 506880 + ... + 538753.

It is an arithmetic number, because the mean of its divisors is an integer number (4166328673).

Almost surely, 2^16664253121 is an apocalyptic number.

It is an amenable number.

16664253121 is a deficient number, since it is larger than the sum of its proper divisors (1061571).

16664253121 is a wasteful number, since it uses less digits than its factorization.

16664253121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1061570.

The product of its digits is 51840, while the sum is 37.

Adding to 16664253121 its reverse (12135246661), we get a palindrome (28799499782).

The spelling of 16664253121 in words is "sixteen billion, six hundred sixty-four million, two hundred fifty-three thousand, one hundred twenty-one".