21438919320 has 256 divisors, whose sum is σ = 81889920000. Its totient is φ = 4367333376.

The previous prime is 21438919303. The next prime is 21438919331. The reversal of 21438919320 is 2391983412.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 282831 + ... + 350529.

It is an arithmetic number, because the mean of its divisors is an integer number (319882500).

Almost surely, 2^21438919320 is an apocalyptic number.

21438919320 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 21438919320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40944960000).

21438919320 is an abundant number, since it is smaller than the sum of its proper divisors (60451000680).

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

21438919320 is a wasteful number, since it uses less digits than its factorization.

21438919320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67762 (or 67758 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 42.

The spelling of 21438919320 in words is "twenty-one billion, four hundred thirty-eight million, nine hundred nineteen thousand, three hundred twenty".