21243634064 has 40 divisors (see below), whose sum is σ = 42505722168. Its totient is φ = 10277591040.

The previous prime is 21243634063. The next prime is 21243634079. The reversal of 21243634064 is 46043634212.

It can be written as a sum of positive squares in 4 ways, for example, as 1473024400 + 19770609664 = 38380^2 + 140608^2 .

It is not an unprimeable number, because it can be changed into a prime (21243634063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8024 + ... + 206280.

Almost surely, 2^21243634064 is an apocalyptic number.

It is an amenable number.

21243634064 is an abundant number, since it is smaller than the sum of its proper divisors (21262088104).

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

21243634064 is a wasteful number, since it uses less digits than its factorization.

21243634064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198483 (or 198477 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 35.

The spelling of 21243634064 in words is "twenty-one billion, two hundred forty-three million, six hundred thirty-four thousand, sixty-four".