21758904720 has 640 divisors, whose sum is σ = 89565696000. Its totient is φ = 4850689536.

The previous prime is 21758904703. The next prime is 21758904749. The reversal of 21758904720 is 2740985712.

It is a happy number.

21758904720 is a `hidden beast` number, since 2 + 1 + 7 + 589 + 0 + 47 + 20 = 666.

It is a super-2 number, since 2×21758904720² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 31857499 + ... + 31858181.

It is an arithmetic number, because the mean of its divisors is an integer number (139946400).

Almost surely, 2^21758904720 is an apocalyptic number.

21758904720 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 21758904720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44782848000).

21758904720 is an abundant number, since it is smaller than the sum of its proper divisors (67806791280).

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

21758904720 is a wasteful number, since it uses less digits than its factorization.

21758904720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769 (or 743 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 45.

The spelling of 21758904720 in words is "twenty-one billion, seven hundred fifty-eight million, nine hundred four thousand, seven hundred twenty".