2121020172 has 36 divisors (see below), whose sum is σ = 5365006920. Its totient is φ = 706540032.

The previous prime is 2121020137. The next prime is 2121020173. The reversal of 2121020172 is 2710201212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is not an unprimeable number, because it can be changed into a prime (2121020173) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38188 + ... + 75500.

It is an arithmetic number, because the mean of its divisors is an integer number (149027970).

Almost surely, 2^2121020172 is an apocalyptic number.

It is an amenable number.

2121020172 is an abundant number, since it is smaller than the sum of its proper divisors (3243986748).

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

2121020172 is a wasteful number, since it uses less digits than its factorization.

2121020172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38902 (or 38897 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 2121020172 is about 46054.5347604337. The cubic root of 2121020172 is about 1284.8376852418.

Adding to 2121020172 its reverse (2710201212), we get a palindrome (4831221384).

The spelling of 2121020172 in words is "two billion, one hundred twenty-one million, twenty thousand, one hundred seventy-two".