21630536172 has 144 divisors (see below), whose sum is σ = 63998206272. Its totient is φ = 6032033280.

The previous prime is 21630536171. The next prime is 21630536183. The reversal of 21630536172 is 27163503612.

21630536172 is a `hidden beast` number, since 2 + 1 + 6 + 30 + 5 + 3 + 617 + 2 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (21630536171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2627022 + ... + 2635242.

It is an arithmetic number, because the mean of its divisors is an integer number (444431988).

Almost surely, 2^21630536172 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 21630536172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31999103136).

21630536172 is an abundant number, since it is smaller than the sum of its proper divisors (42367670100).

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

21630536172 is a wasteful number, since it uses less digits than its factorization.

21630536172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8488 (or 8483 counting only the distinct ones).

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

The spelling of 21630536172 in words is "twenty-one billion, six hundred thirty million, five hundred thirty-six thousand, one hundred seventy-two".