78428869 has 2 divisors, whose sum is σ = 78428870. Its totient is φ = 78428868.

The previous prime is 78428809. The next prime is 78428887. The reversal of 78428869 is 96882487.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56806369 + 21622500 = 7537^2 + 4650^2 .

It is a cyclic number.

It is not a de Polignac number, because 78428869 - 2⁷ = 78428741 is a prime.

It is a super-2 number, since 2×78428869² = 12302174985238322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78428809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39214434 + 39214435.

It is an arithmetic number, because the mean of its divisors is an integer number (39214435).

Almost surely, 2^78428869 is an apocalyptic number.

It is an amenable number.

78428869 is a deficient number, since it is larger than the sum of its proper divisors (1).

78428869 is an equidigital number, since it uses as much as digits as its factorization.

78428869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1548288, while the sum is 52.

The square root of 78428869 is about 8856.0075090302. The cubic root of 78428869 is about 428.0475188891.

It can be divided in two parts, 78428 and 869, that added together give a palindrome (79297).

The spelling of 78428869 in words is "seventy-eight million, four hundred twenty-eight thousand, eight hundred sixty-nine".