21531432312 has 160 divisors (see below), whose sum is σ = 66458533680. Its totient is φ = 6470876160.

The previous prime is 21531432289. The next prime is 21531432319. The reversal of 21531432312 is 21323413512.

21531432312 is a `hidden beast` number, since 2 + 1 + 5 + 314 + 32 + 312 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531432319) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 332512 + ... + 391952.

Almost surely, 2^21531432312 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 21531432312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33229266840).

21531432312 is an abundant number, since it is smaller than the sum of its proper divisors (44927101368).

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

21531432312 is a wasteful number, since it uses less digits than its factorization.

21531432312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59515 (or 59502 counting only the distinct ones).

The product of its digits is 4320, while the sum is 27.

Adding to 21531432312 its reverse (21323413512), we get a palindrome (42854845824).

The spelling of 21531432312 in words is "twenty-one billion, five hundred thirty-one million, four hundred thirty-two thousand, three hundred twelve".