21171533712 has 320 divisors, whose sum is σ = 69986949120. Its totient is φ = 5368799232.

The previous prime is 21171533671. The next prime is 21171533771. The reversal of 21171533712 is 21733517112.

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, 40480683 + ... + 40481205.

It is an arithmetic number, because the mean of its divisors is an integer number (218709216).

Almost surely, 2^21171533712 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 21171533712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34993474560).

21171533712 is an abundant number, since it is smaller than the sum of its proper divisors (48815415408).

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

21171533712 is a wasteful number, since it uses less digits than its factorization.

21171533712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 950 (or 944 counting only the distinct ones).

The product of its digits is 8820, while the sum is 33.

The spelling of 21171533712 in words is "twenty-one billion, one hundred seventy-one million, five hundred thirty-three thousand, seven hundred twelve".