21188634816 has 112 divisors (see below), whose sum is σ = 58927739904. Its totient is φ = 6706292736.

The previous prime is 21188634781. The next prime is 21188634821. The reversal of 21188634816 is 61843688112.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 587481 + ... + 622503.

Almost surely, 2^21188634816 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21188634816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29463869952).

21188634816 is an abundant number, since it is smaller than the sum of its proper divisors (37739105088).

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

21188634816 is a wasteful number, since it uses less digits than its factorization.

21188634816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35198 (or 35188 counting only the distinct ones).

The product of its digits is 442368, while the sum is 48.

The spelling of 21188634816 in words is "twenty-one billion, one hundred eighty-eight million, six hundred thirty-four thousand, eight hundred sixteen".