21505744704 has 56 divisors (see below), whose sum is σ = 57974240160. Its totient is φ = 7033321984.

The previous prime is 21505744613. The next prime is 21505744789. The reversal of 21505744704 is 40744750512.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1046514 + ... + 1066865.

Almost surely, 2^21505744704 is an apocalyptic number.

21505744704 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21505744704 is an abundant number, since it is smaller than the sum of its proper divisors (36468495456).

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

21505744704 is a wasteful number, since it uses less digits than its factorization.

21505744704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2113447 (or 2113437 counting only the distinct ones).

The product of its (nonzero) digits is 156800, while the sum is 39.

The spelling of 21505744704 in words is "twenty-one billion, five hundred five million, seven hundred forty-four thousand, seven hundred four".