21408581880 has 384 divisors, whose sum is σ = 83876083200. Its totient is φ = 4809549312.

The previous prime is 21408581863. The next prime is 21408581881. The reversal of 21408581880 is 8818580412.

21408581880 is a `hidden beast` number, since 21 + 40 + 8 + 581 + 8 + 8 + 0 = 666.

It is a super-2 number, since 2×21408581880² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21408581881) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4011694 + ... + 4017026.

It is an arithmetic number, because the mean of its divisors is an integer number (218427300).

Almost surely, 2^21408581880 is an apocalyptic number.

21408581880 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 21408581880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41938041600).

21408581880 is an abundant number, since it is smaller than the sum of its proper divisors (62467501320).

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

21408581880 is a wasteful number, since it uses less digits than its factorization.

21408581880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5425 (or 5409 counting only the distinct ones).

The product of its (nonzero) digits is 163840, while the sum is 45.

The spelling of 21408581880 in words is "twenty-one billion, four hundred eight million, five hundred eighty-one thousand, eight hundred eighty".