21765812863 has 2 divisors, whose sum is σ = 21765812864. Its totient is φ = 21765812862.

The previous prime is 21765812857. The next prime is 21765812867. The reversal of 21765812863 is 36821856712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21765812863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21765812867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882906431 + 10882906432.

It is an arithmetic number, because the mean of its divisors is an integer number (10882906432).

Almost surely, 2^21765812863 is an apocalyptic number.

21765812863 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765812863 is an equidigital number, since it uses as much as digits as its factorization.

21765812863 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 967680, while the sum is 49.

The spelling of 21765812863 in words is "twenty-one billion, seven hundred sixty-five million, eight hundred twelve thousand, eight hundred sixty-three".