78291257 has 4 divisors (see below), whose sum is σ = 85408656. Its totient is φ = 71173860.

The previous prime is 78291247. The next prime is 78291277. The reversal of 78291257 is 75219287.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 78291257 - 2⁶ = 78291193 is a prime.

It is a super-2 number, since 2×78291257² = 12259041845280098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78291247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3558683 + ... + 3558704.

It is an arithmetic number, because the mean of its divisors is an integer number (21352164).

Almost surely, 2^78291257 is an apocalyptic number.

It is an amenable number.

78291257 is a deficient number, since it is larger than the sum of its proper divisors (7117399).

78291257 is a wasteful number, since it uses less digits than its factorization.

78291257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7117398.

The product of its digits is 70560, while the sum is 41.

The square root of 78291257 is about 8848.2346826924. The cubic root of 78291257 is about 427.7970203122.

The spelling of 78291257 in words is "seventy-eight million, two hundred ninety-one thousand, two hundred fifty-seven".