21045765384 has 144 divisors (see below), whose sum is σ = 68760946800. Its totient is φ = 6013048608.

The previous prime is 21045765337. The next prime is 21045765413. The reversal of 21045765384 is 48356754012.

21045765384 is a `hidden beast` number, since 2 + 1 + 0 + 45 + 76 + 538 + 4 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 15214 + ... + 205725.

It is an arithmetic number, because the mean of its divisors is an integer number (477506575).

Almost surely, 2^21045765384 is an apocalyptic number.

21045765384 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21045765384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34380473400).

21045765384 is an abundant number, since it is smaller than the sum of its proper divisors (47715181416).

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

21045765384 is a wasteful number, since it uses less digits than its factorization.

21045765384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220974 (or 220951 counting only the distinct ones).

The product of its (nonzero) digits is 806400, while the sum is 45.

The spelling of 21045765384 in words is "twenty-one billion, forty-five million, seven hundred sixty-five thousand, three hundred eighty-four".