21659716 has 27 divisors (see below), whose sum is σ = 41275101. Its totient is φ = 9940944.

The previous prime is 21659711. The next prime is 21659719. The reversal of 21659716 is 61795612.

The square root of 21659716 is 4654.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 3204100 + 18455616 = 1790^2 + 4296^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21659711) 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 8 ways as a sum of consecutive naturals, for example, 120915 + ... + 121093.

Almost surely, 2^21659716 is an apocalyptic number.

21659716 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21659716 is the 4654-th square number.

It is an amenable number.

21659716 is a deficient number, since it is larger than the sum of its proper divisors (19615385).

21659716 is a wasteful number, since it uses less digits than its factorization.

21659716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388 (or 194 counting only the distinct ones).

The product of its digits is 22680, while the sum is 37.

The cubic root of 21659716 is about 278.7517393498.

It can be divided in two parts, 21659 and 716, that multiplied together give a square (15507844 = 3938²).

The spelling of 21659716 in words is "twenty-one million, six hundred fifty-nine thousand, seven hundred sixteen".