21708763 has 2 divisors, whose sum is σ = 21708764. Its totient is φ = 21708762.

The previous prime is 21708761. The next prime is 21708781. The reversal of 21708763 is 36780712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21708763 - 2¹ = 21708761 is a prime.

Together with 21708761, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21708761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10854381 + 10854382.

It is an arithmetic number, because the mean of its divisors is an integer number (10854382).

Almost surely, 2^21708763 is an apocalyptic number.

21708763 is a deficient number, since it is larger than the sum of its proper divisors (1).

21708763 is an equidigital number, since it uses as much as digits as its factorization.

21708763 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 21708763 is about 4659.2663585590. The cubic root of 21708763 is about 278.9619857167.

The spelling of 21708763 in words is "twenty-one million, seven hundred eight thousand, seven hundred sixty-three".