21049757784 has 48 divisors (see below), whose sum is σ = 62192468520. Its totient is φ = 6378714240.

The previous prime is 21049757783. The next prime is 21049757797. The reversal of 21049757784 is 48775794012.

21049757784 is a `hidden beast` number, since 2 + 1 + 0 + 497 + 5 + 77 + 84 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21049757784.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21049757783) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13288197 + ... + 13289780.

Almost surely, 2^21049757784 is an apocalyptic number.

21049757784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21049757784 is an abundant number, since it is smaller than the sum of its proper divisors (41142710736).

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

21049757784 is a wasteful number, since it uses less digits than its factorization.

21049757784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26578000 (or 26577993 counting only the distinct ones).

The product of its (nonzero) digits is 3951360, while the sum is 54.

The spelling of 21049757784 in words is "twenty-one billion, forty-nine million, seven hundred fifty-seven thousand, seven hundred eighty-four".