1800138778 has 4 divisors (see below), whose sum is σ = 2700208170. Its totient is φ = 900069388.

The previous prime is 1800138773. The next prime is 1800138797. The reversal of 1800138778 is 8778310081.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8778310081 = 82207 ⋅106783.

It can be written as a sum of positive squares in only one way, i.e., 1641303169 + 158835609 = 40513^2 + 12603^2 .

It is not an unprimeable number, because it can be changed into a prime (1800138773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 450034693 + ... + 450034696.

Almost surely, 2^1800138778 is an apocalyptic number.

1800138778 is a deficient number, since it is larger than the sum of its proper divisors (900069392).

1800138778 is an equidigital number, since it uses as much as digits as its factorization.

1800138778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 900069391.

The product of its (nonzero) digits is 75264, while the sum is 43.

The square root of 1800138778 is about 42428.0423540846. The cubic root of 1800138778 is about 1216.4716603790.

The spelling of 1800138778 in words is "one billion, eight hundred million, one hundred thirty-eight thousand, seven hundred seventy-eight".