21153853440 has 624 divisors, whose sum is σ = 79949140128. Its totient is φ = 5152702464.

The previous prime is 21153853403. The next prime is 21153853447. The reversal of 21153853440 is 4435835112.

21153853440 is a `hidden beast` number, since 2 + 115 + 3 + 8 + 534 + 4 + 0 = 666.

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 = 21153853395 and 21153853404.

It is not an unprimeable number, because it can be changed into a prime (21153853447) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 134737842 + ... + 134737998.

It is an arithmetic number, because the mean of its divisors is an integer number (128123622).

Almost surely, 2^21153853440 is an apocalyptic number.

21153853440 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 21153853440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39974570064).

21153853440 is an abundant number, since it is smaller than the sum of its proper divisors (58795286688).

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

21153853440 is a wasteful number, since it uses less digits than its factorization.

21153853440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 227 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The spelling of 21153853440 in words is "twenty-one billion, one hundred fifty-three million, eight hundred fifty-three thousand, four hundred forty".