21125405532 has 96 divisors (see below), whose sum is σ = 61506869760. Its totient is φ = 5482552320.

The previous prime is 21125405527. The next prime is 21125405537. The reversal of 21125405532 is 23550452112.

It is an interprime number because it is at equal distance from previous prime (21125405527) and next prime (21125405537).

It is a self number, because there is not a number n which added to its sum of digits gives 21125405532.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125405537) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1182168 + ... + 1199904.

It is an arithmetic number, because the mean of its divisors is an integer number (640696560).

Almost surely, 2^21125405532 is an apocalyptic number.

21125405532 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21125405532, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30753434880).

21125405532 is an abundant number, since it is smaller than the sum of its proper divisors (40381464228).

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

21125405532 is a wasteful number, since it uses less digits than its factorization.

21125405532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19051 (or 19049 counting only the distinct ones).

The product of its (nonzero) digits is 12000, while the sum is 30.

Adding to 21125405532 its reverse (23550452112), we get a palindrome (44675857644).

The spelling of 21125405532 in words is "twenty-one billion, one hundred twenty-five million, four hundred five thousand, five hundred thirty-two".