138218777 has 4 divisors (see below), whose sum is σ = 138242916. Its totient is φ = 138194640.

The previous prime is 138218771. The next prime is 138218779. The reversal of 138218777 is 777812831.

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

It can be written as a sum of positive squares in 2 ways, for example, as 45981961 + 92236816 = 6781^2 + 9604^2 .

It is a cyclic number.

It is not a de Polignac number, because 138218777 - 2⁴ = 138218761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138218771) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1943 + ... + 16739.

It is an arithmetic number, because the mean of its divisors is an integer number (34560729).

Almost surely, 2^138218777 is an apocalyptic number.

It is an amenable number.

138218777 is a deficient number, since it is larger than the sum of its proper divisors (24139).

138218777 is an equidigital number, since it uses as much as digits as its factorization.

138218777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24138.

The product of its digits is 131712, while the sum is 44.

The square root of 138218777 is about 11756.6482043140. The cubic root of 138218777 is about 517.0378638556.

The spelling of 138218777 in words is "one hundred thirty-eight million, two hundred eighteen thousand, seven hundred seventy-seven".