2121078778 has 72 divisors (see below), whose sum is σ = 4058576928. Its totient is φ = 828461088.

The previous prime is 2121078749. The next prime is 2121078787. The reversal of 2121078778 is 8778701212.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1373875 + ... + 1375417.

It is an arithmetic number, because the mean of its divisors is an integer number (56369124).

Almost surely, 2^2121078778 is an apocalyptic number.

2121078778 is a deficient number, since it is larger than the sum of its proper divisors (1937498150).

2121078778 is a wasteful number, since it uses less digits than its factorization.

2121078778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1668 (or 1648 counting only the distinct ones).

The product of its (nonzero) digits is 87808, while the sum is 43.

The square root of 2121078778 is about 46055.1710234584. The cubic root of 2121078778 is about 1284.8495189347.

The spelling of 2121078778 in words is "two billion, one hundred twenty-one million, seventy-eight thousand, seven hundred seventy-eight".