21680259 has 4 divisors (see below), whose sum is σ = 28907016. Its totient is φ = 14453504.

The previous prime is 21680257. The next prime is 21680279. The reversal of 21680259 is 95208612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21680259 - 2¹ = 21680257 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21680251) 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, 3613374 + ... + 3613379.

It is an arithmetic number, because the mean of its divisors is an integer number (7226754).

Almost surely, 2^21680259 is an apocalyptic number.

21680259 is a deficient number, since it is larger than the sum of its proper divisors (7226757).

21680259 is an equidigital number, since it uses as much as digits as its factorization.

21680259 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7226756.

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

The square root of 21680259 is about 4656.2065031525. The cubic root of 21680259 is about 278.8398381896.

The spelling of 21680259 in words is "twenty-one million, six hundred eighty thousand, two hundred fifty-nine".