121998387 has 18 divisors (see below), whose sum is σ = 189429924. Its totient is φ = 69636840.

The previous prime is 121998347. The next prime is 121998391. The reversal of 121998387 is 783899121.

It is not a de Polignac number, because 121998387 - 2¹⁸ = 121736243 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121998347) 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 17 ways as a sum of consecutive naturals, for example, 133462 + ... + 134372.

Almost surely, 2^121998387 is an apocalyptic number.

121998387 is a deficient number, since it is larger than the sum of its proper divisors (67431537).

121998387 is an frugal number, since it uses more digits than its factorization.

121998387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1839 (or 921 counting only the distinct ones).

The product of its digits is 217728, while the sum is 48.

The square root of 121998387 is about 11045.2879998667. The cubic root of 121998387 is about 495.9653805940.

Multiplying 121998387 by its sum of digits (48), we get a square (5855922576 = 76524²).

The spelling of 121998387 in words is "one hundred twenty-one million, nine hundred ninety-eight thousand, three hundred eighty-seven".