21444778687 has 2 divisors, whose sum is σ = 21444778688. Its totient is φ = 21444778686.

The previous prime is 21444778633. The next prime is 21444778711. The reversal of 21444778687 is 78687744412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21444778687 - 2⁷ = 21444778559 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21444778787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722389343 + 10722389344.

It is an arithmetic number, because the mean of its divisors is an integer number (10722389344).

Almost surely, 2^21444778687 is an apocalyptic number.

21444778687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21444778687 is an equidigital number, since it uses as much as digits as its factorization.

21444778687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16859136, while the sum is 58.

The spelling of 21444778687 in words is "twenty-one billion, four hundred forty-four million, seven hundred seventy-eight thousand, six hundred eighty-seven".