21354078720 has 320 divisors, whose sum is σ = 77393796480. Its totient is φ = 4979294208.

The previous prime is 21354078679. The next prime is 21354078727. The reversal of 21354078720 is 2787045312.

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21354078727) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1891332 + ... + 1902588.

It is an arithmetic number, because the mean of its divisors is an integer number (241855614).

Almost surely, 2^21354078720 is an apocalyptic number.

21354078720 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 21354078720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38696898240).

21354078720 is an abundant number, since it is smaller than the sum of its proper divisors (56039717760).

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

21354078720 is a wasteful number, since it uses less digits than its factorization.

21354078720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11315 (or 11299 counting only the distinct ones).

The product of its (nonzero) digits is 94080, while the sum is 39.

The spelling of 21354078720 in words is "twenty-one billion, three hundred fifty-four million, seventy-eight thousand, seven hundred twenty".