121778538 has 16 divisors (see below), whose sum is σ = 278351040. Its totient is φ = 34793856.

The previous prime is 121778483. The next prime is 121778557. The reversal of 121778538 is 835877121.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 2899489 = 121778538 / (1 + 2 + 1 + 7 + 7 + 8 + 5 + 3 + 8).

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 121778538.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1449703 + ... + 1449786.

It is an arithmetic number, because the mean of its divisors is an integer number (17396940).

Almost surely, 2^121778538 is an apocalyptic number.

121778538 is an abundant number, since it is smaller than the sum of its proper divisors (156572502).

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

121778538 is a wasteful number, since it uses less digits than its factorization.

121778538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2899501.

The product of its digits is 94080, while the sum is 42.

The square root of 121778538 is about 11035.3313498055. The cubic root of 121778538 is about 495.6672808709.

The spelling of 121778538 in words is "one hundred twenty-one million, seven hundred seventy-eight thousand, five hundred thirty-eight".