21020110010172 has 288 divisors, whose sum is σ = 67231512018944. Its totient is φ = 5388460070400.

The previous prime is 21020110010171. The next prime is 21020110010233. The reversal of 21020110010172 is 27101001102012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020110010171) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 120033597 + ... + 120208587.

Almost surely, 2^{21020110010172} 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 21020110010172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33615756009472).

21020110010172 is an abundant number, since it is smaller than the sum of its proper divisors (46211402008772).

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

21020110010172 is a wasteful number, since it uses less digits than its factorization.

21020110010172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176049 (or 176044 counting only the distinct ones).

The product of its (nonzero) digits is 56, while the sum is 18.

Adding to 21020110010172 its reverse (27101001102012), we get a palindrome (48121111112184).

The spelling of 21020110010172 in words is "twenty-one trillion, twenty billion, one hundred ten million, ten thousand, one hundred seventy-two".