21764921784 has 16 divisors (see below), whose sum is σ = 54412304520. Its totient is φ = 7254973920.

The previous prime is 21764921779. The next prime is 21764921797. The reversal of 21764921784 is 48712946712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 453435847 + ... + 453435894.

Almost surely, 2^21764921784 is an apocalyptic number.

21764921784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21764921784 is an abundant number, since it is smaller than the sum of its proper divisors (32647382736).

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

21764921784 is a wasteful number, since it uses less digits than its factorization.

21764921784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 906871750 (or 906871746 counting only the distinct ones).

The product of its digits is 1354752, while the sum is 51.

The spelling of 21764921784 in words is "twenty-one billion, seven hundred sixty-four million, nine hundred twenty-one thousand, seven hundred eighty-four".