21568505284 has 24 divisors (see below), whose sum is σ = 38259912600. Its totient is φ = 10637679360.

The previous prime is 21568505279. The next prime is 21568505381. The reversal of 21568505284 is 48250586512.

It can be written as a sum of positive squares in 4 ways, for example, as 1093757184 + 20474748100 = 33072^2 + 143090^2 .

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, 77922 + ... + 221830.

It is an arithmetic number, because the mean of its divisors is an integer number (1594163025).

Almost surely, 2^21568505284 is an apocalyptic number.

It is an amenable number.

21568505284 is a deficient number, since it is larger than the sum of its proper divisors (16691407316).

21568505284 is a wasteful number, since it uses less digits than its factorization.

21568505284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144423 (or 144421 counting only the distinct ones).

The product of its (nonzero) digits is 768000, while the sum is 46.

The spelling of 21568505284 in words is "twenty-one billion, five hundred sixty-eight million, five hundred five thousand, two hundred eighty-four".