121221638 has 8 divisors (see below), whose sum is σ = 189738288. Its totient is φ = 57975544.

The previous prime is 121221631. The next prime is 121221641. The reversal of 121221638 is 836122121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121221631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1317581 + ... + 1317672.

It is an arithmetic number, because the mean of its divisors is an integer number (23717286).

Almost surely, 2^121221638 is an apocalyptic number.

121221638 is a deficient number, since it is larger than the sum of its proper divisors (68516650).

121221638 is a wasteful number, since it uses less digits than its factorization.

121221638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2635278.

The product of its digits is 1152, while the sum is 26.

The square root of 121221638 is about 11010.0698453734. The cubic root of 121221638 is about 494.9105548687.

Adding to 121221638 its reverse (836122121), we get a palindrome (957343759).

The spelling of 121221638 in words is "one hundred twenty-one million, two hundred twenty-one thousand, six hundred thirty-eight".