138007778 has 4 divisors (see below), whose sum is σ = 207011670. Its totient is φ = 69003888.

The previous prime is 138007777. The next prime is 138007789. The reversal of 138007778 is 877700831.

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., 119749249 + 18258529 = 10943^2 + 4273^2 .

It is a super-2 number, since 2×138007778² = 38092293576994568, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (138007777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34501943 + ... + 34501946.

Almost surely, 2^138007778 is an apocalyptic number.

138007778 is a deficient number, since it is larger than the sum of its proper divisors (69003892).

138007778 is an equidigital number, since it uses as much as digits as its factorization.

138007778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69003891.

The product of its (nonzero) digits is 65856, while the sum is 41.

The square root of 138007778 is about 11747.6711734709. The cubic root of 138007778 is about 516.7746337438.

The spelling of 138007778 in words is "one hundred thirty-eight million, seven thousand, seven hundred seventy-eight".