21531212352 has 168 divisors, whose sum is σ = 67400424000. Its totient is φ = 6531517440.

The previous prime is 21531212323. The next prime is 21531212363. The reversal of 21531212352 is 25321213512.

21531212352 is a `hidden beast` number, since 2 + 1 + 531 + 2 + 123 + 5 + 2 = 666.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 511399 + ... + 551897.

It is an arithmetic number, because the mean of its divisors is an integer number (401193000).

Almost surely, 2^21531212352 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 21531212352, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33700212000).

21531212352 is an abundant number, since it is smaller than the sum of its proper divisors (45869211648).

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

21531212352 is a wasteful number, since it uses less digits than its factorization.

21531212352 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40601 (or 40588 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

Adding to 21531212352 its reverse (25321213512), we get a palindrome (46852425864).

The spelling of 21531212352 in words is "twenty-one billion, five hundred thirty-one million, two hundred twelve thousand, three hundred fifty-two".