16721226405 has 24 divisors (see below), whose sum is σ = 31212957048. Its totient is φ = 8231988096.

The previous prime is 16721226391. The next prime is 16721226407. The reversal of 16721226405 is 50462212761.

It is a happy number.

16721226405 is a `hidden beast` number, since 1 + 6 + 7 + 2 + 1 + 2 + 2 + 640 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 202293729 + 16518932676 = 14223^2 + 128526^2 .

It is not a de Polignac number, because 16721226405 - 2⁹ = 16721225893 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 16721226405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16721226407) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14291062 + ... + 14292231.

It is an arithmetic number, because the mean of its divisors is an integer number (1300539877).

Almost surely, 2^16721226405 is an apocalyptic number.

16721226405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

16721226405 is a deficient number, since it is larger than the sum of its proper divisors (14491730643).

16721226405 is a wasteful number, since it uses less digits than its factorization.

16721226405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28583317 (or 28583314 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The spelling of 16721226405 in words is "sixteen billion, seven hundred twenty-one million, two hundred twenty-six thousand, four hundred five".