16438136721 has 8 divisors (see below), whose sum is σ = 21918449280. Its totient is φ = 10958290992.

The previous prime is 16438136717. The next prime is 16438136747. The reversal of 16438136721 is 12763183461.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 16438136721 - 2² = 16438136717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16438136321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24030 + ... + 182903.

It is an arithmetic number, because the mean of its divisors is an integer number (2739806160).

Almost surely, 2^16438136721 is an apocalyptic number.

It is an amenable number.

16438136721 is a deficient number, since it is larger than the sum of its proper divisors (5480312559).

16438136721 is a wasteful number, since it uses less digits than its factorization.

16438136721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233415.

The product of its digits is 145152, while the sum is 42.

It can be divided in two parts, 164381 and 36721, that added together give a palindrome (201102).

The spelling of 16438136721 in words is "sixteen billion, four hundred thirty-eight million, one hundred thirty-six thousand, seven hundred twenty-one".