21768118638 has 32 divisors (see below), whose sum is σ = 50437291776. Its totient is φ = 6134263488.

The previous prime is 21768118637. The next prime is 21768118657. The reversal of 21768118638 is 83681186712.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21768118637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3546856 + ... + 3552987.

It is an arithmetic number, because the mean of its divisors is an integer number (1576165368).

Almost surely, 2^21768118638 is an apocalyptic number.

21768118638 is an abundant number, since it is smaller than the sum of its proper divisors (28669173138).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21768118638 is a wasteful number, since it uses less digits than its factorization.

21768118638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7099928.

The product of its digits is 774144, while the sum is 51.

The spelling of 21768118638 in words is "twenty-one billion, seven hundred sixty-eight million, one hundred eighteen thousand, six hundred thirty-eight".