21000068356 has 12 divisors (see below), whose sum is σ = 36752992668. Its totient is φ = 10499213312.

The previous prime is 21000068339. The next prime is 21000068357. The reversal of 21000068356 is 65386000012.

It can be written as a sum of positive squares in 2 ways, for example, as 11105787456 + 9894280900 = 105384^2 + 99470^2 .

It is not an unprimeable number, because it can be changed into a prime (21000068357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145741 + ... + 251476.

It is an arithmetic number, because the mean of its divisors is an integer number (3062749389).

Almost surely, 2^21000068356 is an apocalyptic number.

It is an amenable number.

21000068356 is a deficient number, since it is larger than the sum of its proper divisors (15752924312).

21000068356 is a wasteful number, since it uses less digits than its factorization.

21000068356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410438 (or 410436 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

Adding to 21000068356 its reverse (65386000012), we get a palindrome (86386068368).

The spelling of 21000068356 in words is "twenty-one billion, sixty-eight thousand, three hundred fifty-six".