78638381 has 2 divisors, whose sum is σ = 78638382. Its totient is φ = 78638380.

The previous prime is 78638363. The next prime is 78638387. The reversal of 78638381 is 18383687.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39375625 + 39262756 = 6275^2 + 6266^2 .

It is a cyclic number.

It is not a de Polignac number, because 78638381 - 2¹⁴ = 78621997 is a prime.

It is a super-2 number, since 2×78638381² = 12367989932602322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78638387) 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, 39319190 + 39319191.

It is an arithmetic number, because the mean of its divisors is an integer number (39319191).

Almost surely, 2^78638381 is an apocalyptic number.

It is an amenable number.

78638381 is a deficient number, since it is larger than the sum of its proper divisors (1).

78638381 is an equidigital number, since it uses as much as digits as its factorization.

78638381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 44.

The square root of 78638381 is about 8867.8284263962. The cubic root of 78638381 is about 428.4283367959.

The spelling of 78638381 in words is "seventy-eight million, six hundred thirty-eight thousand, three hundred eighty-one".