21530616372 has 96 divisors (see below), whose sum is σ = 57693941760. Its totient is φ = 6936541920.

The previous prime is 21530616343. The next prime is 21530616383. The reversal of 21530616372 is 27361603512.

21530616372 is a `hidden beast` number, since 2 + 1 + 5 + 3 + 0 + 616 + 37 + 2 = 666.

It is a super-3 number, since 3×21530616372³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

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 31 ways as a sum of consecutive naturals, for example, 2952643 + ... + 2959925.

It is an arithmetic number, because the mean of its divisors is an integer number (600978560).

Almost surely, 2^21530616372 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 21530616372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28846970880).

21530616372 is an abundant number, since it is smaller than the sum of its proper divisors (36163325388).

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

21530616372 is a wasteful number, since it uses less digits than its factorization.

21530616372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8210 (or 8202 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 36.

The spelling of 21530616372 in words is "twenty-one billion, five hundred thirty million, six hundred sixteen thousand, three hundred seventy-two".