2138421778 has 8 divisors (see below), whose sum is σ = 3318240780. Its totient is φ = 1032341520.

The previous prime is 2138421751. The next prime is 2138421787. The reversal of 2138421778 is 8771248312.

It can be written as a sum of positive squares in 2 ways, for example, as 2117564289 + 20857489 = 46017^2 + 4567^2 .

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

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 in 3 ways as a sum of consecutive naturals, for example, 18434613 + ... + 18434728.

Almost surely, 2^2138421778 is an apocalyptic number.

2138421778 is a deficient number, since it is larger than the sum of its proper divisors (1179819002).

2138421778 is a wasteful number, since it uses less digits than its factorization.

2138421778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36869372.

The product of its digits is 150528, while the sum is 43.

The square root of 2138421778 is about 46243.0727569006. The cubic root of 2138421778 is about 1288.3418749802.

The spelling of 2138421778 in words is "two billion, one hundred thirty-eight million, four hundred twenty-one thousand, seven hundred seventy-eight".