21621672216 has 96 divisors (see below), whose sum is σ = 61114716000. Its totient is φ = 6897042432.

The previous prime is 21621672211. The next prime is 21621672217. The reversal of 21621672216 is 61227612612.

It is a happy number.

21621672216 is a `hidden beast` number, since 2 + 1 + 621 + 6 + 7 + 2 + 21 + 6 = 666.

It is a super-2 number, since 2×21621672216² (a number of 21 digits) contains 22 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 not an unprimeable number, because it can be changed into a prime (21621672211) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 190125 + ... + 281763.

It is an arithmetic number, because the mean of its divisors is an integer number (636611625).

Almost surely, 2^21621672216 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 21621672216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30557358000).

21621672216 is an abundant number, since it is smaller than the sum of its proper divisors (39493043784).

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

21621672216 is a wasteful number, since it uses less digits than its factorization.

21621672216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91793 (or 91786 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The spelling of 21621672216 in words is "twenty-one billion, six hundred twenty-one million, six hundred seventy-two thousand, two hundred sixteen".