12121100172 has 30 divisors (see below), whose sum is σ = 31686950988. Its totient is φ = 4040366616.

The previous prime is 12121100171. The next prime is 12121100209. The reversal of 12121100172 is 27100112121.

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 (12121100171) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 18705078 + ... + 18705725.

Almost surely, 2^12121100172 is an apocalyptic number.

12121100172 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

12121100172 is an abundant number, since it is smaller than the sum of its proper divisors (19565850816).

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

12121100172 is a wasteful number, since it uses less digits than its factorization.

12121100172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37410819 (or 37410808 counting only the distinct ones).

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

Adding to 12121100172 its reverse (27100112121), we get a palindrome (39221212293).

The spelling of 12121100172 in words is "twelve billion, one hundred twenty-one million, one hundred thousand, one hundred seventy-two".