21602354021172 has 18 divisors (see below), whose sum is σ = 54605950442498. Its totient is φ = 7200784673712.

The previous prime is 21602354021153. The next prime is 21602354021177. The reversal of 21602354021172 is 27112045320612.

21602354021172 is a `hidden beast` number, since 2 + 1 + 6 + 0 + 23 + 540 + 21 + 1 + 72 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11077753962276 + 10524600058896 = 3328326^2 + 3244164^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 600065389477 = 21602354021172 / (2 + 1 + 6 + 0 + 2 + 3 + 5 + 4 + 0 + 2 + 1 + 1 + 7 + 2).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21602354021177) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 300032694703 + ... + 300032694774.

Almost surely, 2^{21602354021172} is an apocalyptic number.

It is an amenable number.

21602354021172 is an abundant number, since it is smaller than the sum of its proper divisors (33003596421326).

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

21602354021172 is a wasteful number, since it uses less digits than its factorization.

21602354021172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 600065389487 (or 600065389482 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

Adding to 21602354021172 its reverse (27112045320612), we get a palindrome (48714399341784).

The spelling of 21602354021172 in words is "twenty-one trillion, six hundred two billion, three hundred fifty-four million, twenty-one thousand, one hundred seventy-two".