21016656 has 30 divisors (see below), whose sum is σ = 58817850. Its totient is φ = 7005504.

The previous prime is 21016651. The next prime is 21016657. The reversal of 21016656 is 65661012.

It is a happy number.

21016656 is a `hidden beast` number, since 2 + 1 + 0 + 1 + 6 + 656 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21013056 + 3600 = 4584^2 + 60^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21016651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 72831 + ... + 73118.

It is an arithmetic number, because the mean of its divisors is an integer number (1960595).

Almost surely, 2^21016656 is an apocalyptic number.

It is an amenable number.

21016656 is an abundant number, since it is smaller than the sum of its proper divisors (37801194).

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

21016656 is a wasteful number, since it uses less digits than its factorization.

21016656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145963 (or 145954 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21016656 is about 4584.3926533402. The cubic root of 21016656 is about 275.9653390626.

Adding to 21016656 its reverse (65661012), we get a palindrome (86677668).

The spelling of 21016656 in words is "twenty-one million, sixteen thousand, six hundred fifty-six".