21005621532 has 144 divisors (see below), whose sum is σ = 67634461440. Its totient is φ = 5351256576.

The previous prime is 21005621521. The next prime is 21005621543. The reversal of 21005621532 is 23512650012.

It is a happy number.

21005621532 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 5 + 621 + 5 + 32 = 666.

It is an interprime number because it is at equal distance from previous prime (21005621521) and next prime (21005621543).

It is a super-2 number, since 2×21005621532² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21005621496 and 21005621505.

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 47638 + ... + 210429.

It is an arithmetic number, because the mean of its divisors is an integer number (469683760).

Almost surely, 2^21005621532 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 21005621532, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33817230720).

21005621532 is an abundant number, since it is smaller than the sum of its proper divisors (46628839908).

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

21005621532 is a wasteful number, since it uses less digits than its factorization.

21005621532 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258120 (or 258115 counting only the distinct ones).

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

The spelling of 21005621532 in words is "twenty-one billion, five million, six hundred twenty-one thousand, five hundred thirty-two".