21531112002 has 96 divisors (see below), whose sum is σ = 50620377600. Its totient is φ = 6598537344.

The previous prime is 21531111971. The next prime is 21531112003. The reversal of 21531112002 is 20021113512.

21531112002 is a `hidden beast` number, since 21 + 531 + 112 + 0 + 0 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21531112003) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 895899 + ... + 919617.

It is an arithmetic number, because the mean of its divisors is an integer number (527295600).

Almost surely, 2^21531112002 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21531112002, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25310188800).

21531112002 is an abundant number, since it is smaller than the sum of its proper divisors (29089265598).

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

21531112002 is a wasteful number, since it uses less digits than its factorization.

21531112002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23840 (or 23837 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

Adding to 21531112002 its reverse (20021113512), we get a palindrome (41552225514).

The spelling of 21531112002 in words is "twenty-one billion, five hundred thirty-one million, one hundred twelve thousand, two".