21680529 has 16 divisors (see below), whose sum is σ = 31215744. Its totient is φ = 13305600.

The previous prime is 21680497. The next prime is 21680587. The reversal of 21680529 is 92508612.

It is not a de Polignac number, because 21680529 - 2⁵ = 21680497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21680529.

It is not an unprimeable number, because it can be changed into a prime (21680629) 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 15 ways as a sum of consecutive naturals, for example, 24169 + ... + 25049.

It is an arithmetic number, because the mean of its divisors is an integer number (1950984).

Almost surely, 2^21680529 is an apocalyptic number.

It is an amenable number.

21680529 is a deficient number, since it is larger than the sum of its proper divisors (9535215).

21680529 is a wasteful number, since it uses less digits than its factorization.

21680529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1528.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21680529 is about 4656.2354966217. The cubic root of 21680529 is about 278.8409957164.

The spelling of 21680529 in words is "twenty-one million, six hundred eighty thousand, five hundred twenty-nine".