21559616 has 28 divisors (see below), whose sum is σ = 46075092. Its totient is φ = 9950208.

The previous prime is 21559613. The next prime is 21559639. The reversal of 21559616 is 61695512.

It can be written as a sum of positive squares in 2 ways, for example, as 7840000 + 13719616 = 2800^2 + 3704^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21559613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12125 + ... + 13788.

It is an arithmetic number, because the mean of its divisors is an integer number (1645539).

Almost surely, 2^21559616 is an apocalyptic number.

21559616 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21559616 is an abundant number, since it is smaller than the sum of its proper divisors (24515476).

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

21559616 is a wasteful number, since it uses less digits than its factorization.

21559616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25938 (or 25928 counting only the distinct ones).

The product of its digits is 16200, while the sum is 35.

The square root of 21559616 is about 4643.2333561862. The cubic root of 21559616 is about 278.3216606991.

The spelling of 21559616 in words is "twenty-one million, five hundred fifty-nine thousand, six hundred sixteen".