21780700663 has 2 divisors, whose sum is σ = 21780700664. Its totient is φ = 21780700662.

The previous prime is 21780700649. The next prime is 21780700681. The reversal of 21780700663 is 36600708712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21780700663 - 2⁵ = 21780700631 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21780700633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10890350331 + 10890350332.

It is an arithmetic number, because the mean of its divisors is an integer number (10890350332).

Almost surely, 2^21780700663 is an apocalyptic number.

21780700663 is a deficient number, since it is larger than the sum of its proper divisors (1).

21780700663 is an equidigital number, since it uses as much as digits as its factorization.

21780700663 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84672, while the sum is 40.

The spelling of 21780700663 in words is "twenty-one billion, seven hundred eighty million, seven hundred thousand, six hundred sixty-three".