21002122172 has 24 divisors (see below), whose sum is σ = 37945152000. Its totient is φ = 10160754480.

The previous prime is 21002122171. The next prime is 21002122213. The reversal of 21002122172 is 27122120012.

It is a super-2 number, since 2×21002122172² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002122171) 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, 1549079 + ... + 1562577.

It is an arithmetic number, because the mean of its divisors is an integer number (1581048000).

Almost surely, 2^21002122172 is an apocalyptic number.

It is an amenable number.

21002122172 is a deficient number, since it is larger than the sum of its proper divisors (16943029828).

21002122172 is a wasteful number, since it uses less digits than its factorization.

21002122172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26081 (or 26079 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

Adding to 21002122172 its reverse (27122120012), we get a palindrome (48124242184).

The spelling of 21002122172 in words is "twenty-one billion, two million, one hundred twenty-two thousand, one hundred seventy-two".