78812257 has 4 divisors (see below), whose sum is σ = 80942356. Its totient is φ = 76682160.

The previous prime is 78812233. The next prime is 78812267. The reversal of 78812257 is 75221887.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 50253921 + 28558336 = 7089^2 + 5344^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78812257 is a prime.

It is a super-2 number, since 2×78812257² = 12422743706868098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78812207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1064994 + ... + 1065067.

It is an arithmetic number, because the mean of its divisors is an integer number (20235589).

Almost surely, 2^78812257 is an apocalyptic number.

It is an amenable number.

78812257 is a deficient number, since it is larger than the sum of its proper divisors (2130099).

78812257 is a wasteful number, since it uses less digits than its factorization.

78812257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2130098.

The product of its digits is 62720, while the sum is 40.

The square root of 78812257 is about 8877.6267662028. The cubic root of 78812257 is about 428.7438679151.

The spelling of 78812257 in words is "seventy-eight million, eight hundred twelve thousand, two hundred fifty-seven".