21210005172 has 48 divisors (see below), whose sum is σ = 50186404800. Its totient is φ = 6971212032.

The previous prime is 21210005111. The next prime is 21210005177. The reversal of 21210005172 is 27150001212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210005177) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 201663 + ... + 288249.

It is an arithmetic number, because the mean of its divisors is an integer number (1045550100).

Almost surely, 2^21210005172 is an apocalyptic number.

It is an amenable number.

21210005172 is an abundant number, since it is smaller than the sum of its proper divisors (28976399628).

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

21210005172 is a wasteful number, since it uses less digits than its factorization.

21210005172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86880 (or 86878 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 21.

Adding to 21210005172 its reverse (27150001212), we get a palindrome (48360006384).

The spelling of 21210005172 in words is "twenty-one billion, two hundred ten million, five thousand, one hundred seventy-two".