21501381384 has 48 divisors (see below), whose sum is σ = 66551896320. Its totient is φ = 6143251680.

The previous prime is 21501381367. The next prime is 21501381389. The reversal of 21501381384 is 48318310512.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21501381389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21330232 + ... + 21331239.

It is an arithmetic number, because the mean of its divisors is an integer number (1386497840).

Almost surely, 2^21501381384 is an apocalyptic number.

21501381384 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21501381384 is an abundant number, since it is smaller than the sum of its proper divisors (45050514936).

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

21501381384 is a wasteful number, since it uses less digits than its factorization.

21501381384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42661490 (or 42661483 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

Adding to 21501381384 its reverse (48318310512), we get a palindrome (69819691896).

The spelling of 21501381384 in words is "twenty-one billion, five hundred one million, three hundred eighty-one thousand, three hundred eighty-four".