21220101212172 has 24 divisors (see below), whose sum is σ = 49521127848192. Its totient is φ = 7072287306000.

The previous prime is 21220101212081. The next prime is 21220101212173. The reversal of 21220101212172 is 27121210102212.

It is not an unprimeable number, because it can be changed into a prime (21220101212173) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 134888704 + ... + 135045927.

It is an arithmetic number, because the mean of its divisors is an integer number (2063380327008).

Almost surely, 2^{21220101212172} is an apocalyptic number.

It is an amenable number.

21220101212172 is an abundant number, since it is smaller than the sum of its proper divisors (28301026636020).

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

21220101212172 is a wasteful number, since it uses less digits than its factorization.

21220101212172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269941189 (or 269941187 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 24.

Adding to 21220101212172 its reverse (27121210102212), we get a palindrome (48341311314384).

The spelling of 21220101212172 in words is "twenty-one trillion, two hundred twenty billion, one hundred one million, two hundred twelve thousand, one hundred seventy-two".