21504421380 has 48 divisors (see below), whose sum is σ = 64844103744. Its totient is φ = 5293395840.

The previous prime is 21504421333. The next prime is 21504421387. The reversal of 21504421380 is 8312440512.

It is a super-2 number, since 2×21504421380² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21504421387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13784106 + ... + 13785665.

It is an arithmetic number, because the mean of its divisors is an integer number (1350918828).

Almost surely, 2^21504421380 is an apocalyptic number.

21504421380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21504421380 is an abundant number, since it is smaller than the sum of its proper divisors (43339682364).

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

21504421380 is a wasteful number, since it uses less digits than its factorization.

21504421380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27569796 (or 27569794 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

Adding to 21504421380 its reverse (8312440512), we get a palindrome (29816861892).

The spelling of 21504421380 in words is "twenty-one billion, five hundred four million, four hundred twenty-one thousand, three hundred eighty".