78178649 has 2 divisors, whose sum is σ = 78178650. Its totient is φ = 78178648.

The previous prime is 78178643. The next prime is 78178691. The reversal of 78178649 is 94687187.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74511424 + 3667225 = 8632^2 + 1915^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78178649 is a prime.

It is a super-2 number, since 2×78178649² = 12223802318930402, which contains 22 as substring.

It is a Chen prime.

It is a plaindrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 78178597 and 78178606.

It is not a weakly prime, because it can be changed into another prime (78178643) 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, 39089324 + 39089325.

It is an arithmetic number, because the mean of its divisors is an integer number (39089325).

Almost surely, 2^78178649 is an apocalyptic number.

It is an amenable number.

78178649 is a deficient number, since it is larger than the sum of its proper divisors (1).

78178649 is an equidigital number, since it uses as much as digits as its factorization.

78178649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 677376, while the sum is 50.

The square root of 78178649 is about 8841.8690897344. The cubic root of 78178649 is about 427.5918186781.

The spelling of 78178649 in words is "seventy-eight million, one hundred seventy-eight thousand, six hundred forty-nine".