21538712832 has 216 divisors, whose sum is σ = 71814599136. Its totient is φ = 5680410624.

The previous prime is 21538712831. The next prime is 21538712837. The reversal of 21538712832 is 23821783512.

It is a super-2 number, since 2×21538712832² (a number of 21 digits) contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21538712831) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 467203 + ... + 511229.

It is an arithmetic number, because the mean of its divisors is an integer number (332474996).

Almost surely, 2^21538712832 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21538712832, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35907299568).

21538712832 is an abundant number, since it is smaller than the sum of its proper divisors (50275886304).

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

21538712832 is a wasteful number, since it uses less digits than its factorization.

21538712832 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44073 (or 44052 counting only the distinct ones).

The product of its digits is 161280, while the sum is 42.

The spelling of 21538712832 in words is "twenty-one billion, five hundred thirty-eight million, seven hundred twelve thousand, eight hundred thirty-two".