21642643440 has 240 divisors, whose sum is σ = 79643697120. Its totient is φ = 5223352320.

The previous prime is 21642643417. The next prime is 21642643483. The reversal of 21642643440 is 4434624612.

21642643440 is a `hidden beast` number, since 2 + 1 + 6 + 4 + 2 + 643 + 4 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

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

It is a junction number, because it is equal to n+sod(n) for n = 21642643395 and 21642643404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1807714 + ... + 1819646.

It is an arithmetic number, because the mean of its divisors is an integer number (331848738).

Almost surely, 2^21642643440 is an apocalyptic number.

21642643440 is a gapful number since it is divisible by the number (20) 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 21642643440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39821848560).

21642643440 is an abundant number, since it is smaller than the sum of its proper divisors (58001053680).

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

21642643440 is a wasteful number, since it uses less digits than its factorization.

21642643440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12192 (or 12183 counting only the distinct ones).

The product of its (nonzero) digits is 110592, while the sum is 36.

The spelling of 21642643440 in words is "twenty-one billion, six hundred forty-two million, six hundred forty-three thousand, four hundred forty".