21385522768 has 10 divisors (see below), whose sum is σ = 41434450394. Its totient is φ = 10692761376.

The previous prime is 21385522747. The next prime is 21385522799. The reversal of 21385522768 is 86722558312.

It can be written as a sum of positive squares in only one way, i.e., 17633715264 + 3751807504 = 132792^2 + 61252^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 668297571 + ... + 668297602.

Almost surely, 2^21385522768 is an apocalyptic number.

It is an amenable number.

21385522768 is a deficient number, since it is larger than the sum of its proper divisors (20048927626).

21385522768 is a wasteful number, since it uses less digits than its factorization.

21385522768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1336595181 (or 1336595175 counting only the distinct ones).

The product of its digits is 1612800, while the sum is 49.

The spelling of 21385522768 in words is "twenty-one billion, three hundred eighty-five million, five hundred twenty-two thousand, seven hundred sixty-eight".