21951778699 has 2 divisors, whose sum is σ = 21951778700. Its totient is φ = 21951778698.

The previous prime is 21951778697. The next prime is 21951778747. The reversal of 21951778699 is 99687715912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21951778699 - 2¹ = 21951778697 is a prime.

Together with 21951778697, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21951778699.

It is not a weakly prime, because it can be changed into another prime (21951778697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10975889349 + 10975889350.

It is an arithmetic number, because the mean of its divisors is an integer number (10975889350).

Almost surely, 2^21951778699 is an apocalyptic number.

21951778699 is a deficient number, since it is larger than the sum of its proper divisors (1).

21951778699 is an equidigital number, since it uses as much as digits as its factorization.

21951778699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17146080, while the sum is 64.

The spelling of 21951778699 in words is "twenty-one billion, nine hundred fifty-one million, seven hundred seventy-eight thousand, six hundred ninety-nine".