78390889 has 2 divisors, whose sum is σ = 78390890. Its totient is φ = 78390888.

The previous prime is 78390883. The next prime is 78390899. The reversal of 78390889 is 98809387.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66259600 + 12131289 = 8140^2 + 3483^2 .

It is a cyclic number.

It is not a de Polignac number, because 78390889 - 2¹⁵ = 78358121 is a prime.

It is a super-2 number, since 2×78390889² = 12290262956420642, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78390883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39195444 + 39195445.

It is an arithmetic number, because the mean of its divisors is an integer number (39195445).

Almost surely, 2^78390889 is an apocalyptic number.

It is an amenable number.

78390889 is a deficient number, since it is larger than the sum of its proper divisors (1).

78390889 is an equidigital number, since it uses as much as digits as its factorization.

78390889 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 870912, while the sum is 52.

The square root of 78390889 is about 8853.8629422417. The cubic root of 78390889 is about 427.9784122369.

The spelling of 78390889 in words is "seventy-eight million, three hundred ninety thousand, eight hundred eighty-nine".