121820172 has 72 divisors (see below), whose sum is σ = 305574192. Its totient is φ = 37756800.

The previous prime is 121820159. The next prime is 121820183. The reversal of 121820172 is 271028121.

It is a super-2 number, since 2×121820172² = 29680308612219168, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 264022 + ... + 264482.

It is an arithmetic number, because the mean of its divisors is an integer number (4244086).

Almost surely, 2^121820172 is an apocalyptic number.

121820172 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 121820172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (152787096).

121820172 is an abundant number, since it is smaller than the sum of its proper divisors (183754020).

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

121820172 is a wasteful number, since it uses less digits than its factorization.

121820172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 567 (or 546 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 24.

The square root of 121820172 is about 11037.2175841559. The cubic root of 121820172 is about 495.7237611577.

Adding to 121820172 its reverse (271028121), we get a palindrome (392848293).

The spelling of 121820172 in words is "one hundred twenty-one million, eight hundred twenty thousand, one hundred seventy-two".