16663840381 has 4 divisors (see below), whose sum is σ = 16676085564. Its totient is φ = 16651595200.

The previous prime is 16663840379. The next prime is 16663840397. The reversal of 16663840381 is 18304836661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18304836661 = 3079 ⋅5945059.

It can be written as a sum of positive squares in 2 ways, for example, as 10354080025 + 6309760356 = 101755^2 + 79434^2 .

It is a cyclic number.

It is not a de Polignac number, because 16663840381 - 2¹ = 16663840379 is a prime.

It is a super-2 number, since 2×16663840381² (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 (16663840301) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 6120550 + ... + 6123271.

It is an arithmetic number, because the mean of its divisors is an integer number (4169021391).

Almost surely, 2^16663840381 is an apocalyptic number.

It is an amenable number.

16663840381 is a deficient number, since it is larger than the sum of its proper divisors (12245183).

16663840381 is a wasteful number, since it uses less digits than its factorization.

16663840381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12245182.

The product of its (nonzero) digits is 497664, while the sum is 46.

The spelling of 16663840381 in words is "sixteen billion, six hundred sixty-three million, eight hundred forty thousand, three hundred eighty-one".