78138149 has 2 divisors, whose sum is σ = 78138150. Its totient is φ = 78138148.

The previous prime is 78138143. The next prime is 78138157. The reversal of 78138149 is 94183187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44289025 + 33849124 = 6655^2 + 5818^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78138149 is a prime.

It is a super-2 number, since 2×78138149² = 12211140658292402, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78138143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39069074 + 39069075.

It is an arithmetic number, because the mean of its divisors is an integer number (39069075).

Almost surely, 2^78138149 is an apocalyptic number.

It is an amenable number.

78138149 is a deficient number, since it is larger than the sum of its proper divisors (1).

78138149 is an equidigital number, since it uses as much as digits as its factorization.

78138149 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 41.

The square root of 78138149 is about 8839.5785533022. The cubic root of 78138149 is about 427.5179687624.

It can be divided in two parts, 78138 and 149, that added together give a palindrome (78287).

The spelling of 78138149 in words is "seventy-eight million, one hundred thirty-eight thousand, one hundred forty-nine".