21664116 has 36 divisors (see below), whose sum is σ = 55125252. Its totient is φ = 7173504.

The previous prime is 21664109. The next prime is 21664117. The reversal of 21664116 is 61146612.

21664116 is a `hidden beast` number, since 2 + 1 + 6 + 641 + 16 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 5503716 + 16160400 = 2346^2 + 4020^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21664116² = 938667844122912, which contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21664116.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3736 + ... + 7568.

It is an arithmetic number, because the mean of its divisors is an integer number (1531257).

Almost surely, 2^21664116 is an apocalyptic number.

It is an amenable number.

21664116 is an abundant number, since it is smaller than the sum of its proper divisors (33461136).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21664116 is a wasteful number, since it uses less digits than its factorization.

21664116 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4000 (or 3995 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 21664116 is about 4654.4726876414. The cubic root of 21664116 is about 278.7706134756.

The spelling of 21664116 in words is "twenty-one million, six hundred sixty-four thousand, one hundred sixteen".