21864121344 has 352 divisors, whose sum is σ = 70686676480. Its totient is φ = 6718464000.

The previous prime is 21864121339. The next prime is 21864121393. The reversal of 21864121344 is 44312146812.

21864121344 is a `hidden beast` number, since 2 + 1 + 8 + 641 + 2 + 1 + 3 + 4 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

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

It is a junction number, because it is equal to n+sod(n) for n = 21864121299 and 21864121308.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 29112969 + ... + 29113719.

Almost surely, 2^21864121344 is an apocalyptic number.

21864121344 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21864121344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35343338240).

21864121344 is an abundant number, since it is smaller than the sum of its proper divisors (48822555136).

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

21864121344 is an frugal number, since it uses more digits than its factorization.

21864121344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805 (or 769 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The spelling of 21864121344 in words is "twenty-one billion, eight hundred sixty-four million, one hundred twenty-one thousand, three hundred forty-four".