121638825 has 216 divisors, whose sum is σ = 297704160. Its totient is φ = 46771200.

The previous prime is 121638809. The next prime is 121638827. The reversal of 121638825 is 528836121.

It is a happy number.

121638825 is a `hidden beast` number, since 12 + 1 + 638 + 8 + 2 + 5 = 666.

It is not a de Polignac number, because 121638825 - 2⁴ = 121638809 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 121638825.

It is not an unprimeable number, because it can be changed into a prime (121638827) by changing a digit.

It is a polite number, since it can be written in 215 ways as a sum of consecutive naturals, for example, 2061646 + ... + 2061704.

It is an arithmetic number, because the mean of its divisors is an integer number (1378260).

Almost surely, 2^121638825 is an apocalyptic number.

121638825 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

121638825 is an abundant number, since it is smaller than the sum of its proper divisors (176065335).

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

121638825 is a wasteful number, since it uses less digits than its factorization.

121638825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 102 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 121638825 is about 11028.9992746396. Note that the first 3 decimals coincide. The cubic root of 121638825 is about 495.4776534151.

The spelling of 121638825 in words is "one hundred twenty-one million, six hundred thirty-eight thousand, eight hundred twenty-five".