78091231 has 2 divisors, whose sum is σ = 78091232. Its totient is φ = 78091230.

The previous prime is 78091219. The next prime is 78091241. The reversal of 78091231 is 13219087.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78091231 - 2⁵ = 78091199 is a prime.

It is a super-2 number, since 2×78091231² = 12196480718190722, which contains 22 as substring.

It is equal to p_4564561 and since 78091231 and 4564561 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 78091193 and 78091202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78091241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39045615 + 39045616.

It is an arithmetic number, because the mean of its divisors is an integer number (39045616).

Almost surely, 2^78091231 is an apocalyptic number.

78091231 is a deficient number, since it is larger than the sum of its proper divisors (1).

78091231 is an equidigital number, since it uses as much as digits as its factorization.

78091231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 78091231 is about 8836.9242952511. The cubic root of 78091231 is about 427.4323840030.

It can be divided in two parts, 78091 and 231, that multiplied together give a triangular number (18039021 = T₆₀₀₆).

The spelling of 78091231 in words is "seventy-eight million, ninety-one thousand, two hundred thirty-one".