21451139688 has 512 divisors, whose sum is σ = 67682304000. Its totient is φ = 5588352000.

The previous prime is 21451139683. The next prime is 21451139713. The reversal of 21451139688 is 88693115412.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21451139683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 302128693 + ... + 302128763.

It is an arithmetic number, because the mean of its divisors is an integer number (132192000).

Almost surely, 2^21451139688 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 21451139688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33841152000).

21451139688 is an abundant number, since it is smaller than the sum of its proper divisors (46231164312).

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

21451139688 is a wasteful number, since it uses less digits than its factorization.

21451139688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 237 (or 233 counting only the distinct ones).

The product of its digits is 414720, while the sum is 48.

The spelling of 21451139688 in words is "twenty-one billion, four hundred fifty-one million, one hundred thirty-nine thousand, six hundred eighty-eight".