21680635 has 8 divisors (see below), whose sum is σ = 26373600. Its totient is φ = 17106624.

The previous prime is 21680629. The next prime is 21680639. The reversal of 21680635 is 53608612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21680635 - 2²¹ = 19583483 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21680597 and 21680606.

It is not an unprimeable number, because it can be changed into a prime (21680639) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29335 + ... + 30064.

It is an arithmetic number, because the mean of its divisors is an integer number (3296700).

Almost surely, 2^21680635 is an apocalyptic number.

21680635 is a deficient number, since it is larger than the sum of its proper divisors (4692965).

21680635 is an equidigital number, since it uses as much as digits as its factorization.

21680635 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59477.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 21680635 is about 4656.2468791936. The cubic root of 21680635 is about 278.8414501502.

The spelling of 21680635 in words is "twenty-one million, six hundred eighty thousand, six hundred thirty-five".