78318731 has 4 divisors (see below), whose sum is σ = 78408912. Its totient is φ = 78228552.

The previous prime is 78318697. The next prime is 78318739. The reversal of 78318731 is 13781387.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13781387 = 47 ⋅293221.

It is a cyclic number.

It is not a de Polignac number, because 78318731 - 2¹⁴ = 78302347 is a prime.

It is a super-2 number, since 2×78318731² = 12267647250900722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78318739) 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, 43775 + ... + 45528.

It is an arithmetic number, because the mean of its divisors is an integer number (19602228).

Almost surely, 2^78318731 is an apocalyptic number.

78318731 is a deficient number, since it is larger than the sum of its proper divisors (90181).

78318731 is an equidigital number, since it uses as much as digits as its factorization.

78318731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90180.

The product of its digits is 28224, while the sum is 38.

The square root of 78318731 is about 8849.7870595851. The cubic root of 78318731 is about 427.8470553618.

The spelling of 78318731 in words is "seventy-eight million, three hundred eighteen thousand, seven hundred thirty-one".