21680807 has 2 divisors, whose sum is σ = 21680808. Its totient is φ = 21680806.

The previous prime is 21680801. The next prime is 21680819. The reversal of 21680807 is 70808612.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21680807 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21680801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10840403 + 10840404.

It is an arithmetic number, because the mean of its divisors is an integer number (10840404).

Almost surely, 2^21680807 is an apocalyptic number.

21680807 is a deficient number, since it is larger than the sum of its proper divisors (1).

21680807 is an equidigital number, since it uses as much as digits as its factorization.

21680807 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 21680807 is about 4656.2653489680. The cubic root of 21680807 is about 278.8421875303.

The spelling of 21680807 in words is "twenty-one million, six hundred eighty thousand, eight hundred seven".