16638540681 has 16 divisors (see below), whose sum is σ = 25674905600. Its totient is φ = 9387385488.

The previous prime is 16638540601. The next prime is 16638540683. The reversal of 16638540681 is 18604583661.

It is not a de Polignac number, because 16638540681 - 2¹³ = 16638532489 is a prime.

It is a super-2 number, since 2×16638540681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16638540681.

It is not an unprimeable number, because it can be changed into a prime (16638540683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5012971 + ... + 5016288.

It is an arithmetic number, because the mean of its divisors is an integer number (1604681600).

Almost surely, 2^16638540681 is an apocalyptic number.

It is an amenable number.

16638540681 is a deficient number, since it is larger than the sum of its proper divisors (9036364919).

16638540681 is a wasteful number, since it uses less digits than its factorization.

16638540681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10029348.

The product of its (nonzero) digits is 829440, while the sum is 48.

The spelling of 16638540681 in words is "sixteen billion, six hundred thirty-eight million, five hundred forty thousand, six hundred eighty-one".