2129218778 has 4 divisors (see below), whose sum is σ = 3193828170. Its totient is φ = 1064609388.

The previous prime is 2129218759. The next prime is 2129218789. The reversal of 2129218778 is 8778129212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1800050329 + 329168449 = 42427^2 + 18143^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 532304693 + ... + 532304696.

Almost surely, 2^2129218778 is an apocalyptic number.

2129218778 is a deficient number, since it is larger than the sum of its proper divisors (1064609392).

2129218778 is a wasteful number, since it uses less digits than its factorization.

2129218778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1064609391.

The product of its digits is 225792, while the sum is 47.

The square root of 2129218778 is about 46143.4586696749. The cubic root of 2129218778 is about 1286.4910302674.

The spelling of 2129218778 in words is "two billion, one hundred twenty-nine million, two hundred eighteen thousand, seven hundred seventy-eight".