21786891764 has 24 divisors (see below), whose sum is σ = 42607627776. Its totient is φ = 9661592000.

The previous prime is 21786891761. The next prime is 21786891787. The reversal of 21786891764 is 46719868712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21786891761) 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 7 ways as a sum of consecutive naturals, for example, 6036692 + ... + 6040299.

It is an arithmetic number, because the mean of its divisors is an integer number (1775317824).

Almost surely, 2^21786891764 is an apocalyptic number.

It is an amenable number.

21786891764 is a deficient number, since it is larger than the sum of its proper divisors (20820736012).

21786891764 is a wasteful number, since it uses less digits than its factorization.

21786891764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12077047 (or 12077045 counting only the distinct ones).

The product of its digits is 8128512, while the sum is 59.

The spelling of 21786891764 in words is "twenty-one billion, seven hundred eighty-six million, eight hundred ninety-one thousand, seven hundred sixty-four".