21765983 has 2 divisors, whose sum is σ = 21765984. Its totient is φ = 21765982.

The previous prime is 21765977. The next prime is 21766007. The reversal of 21765983 is 38956712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21765983 - 2¹⁰ = 21764959 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21765983.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21765923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882991 + 10882992.

It is an arithmetic number, because the mean of its divisors is an integer number (10882992).

Almost surely, 2^21765983 is an apocalyptic number.

21765983 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765983 is an equidigital number, since it uses as much as digits as its factorization.

21765983 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 41.

The square root of 21765983 is about 4665.4027693223. The cubic root of 21765983 is about 279.2068668724.

The spelling of 21765983 in words is "twenty-one million, seven hundred sixty-five thousand, nine hundred eighty-three".