78640231 has 4 divisors (see below), whose sum is σ = 78660000. Its totient is φ = 78620464.

The previous prime is 78640229. The next prime is 78640271. The reversal of 78640231 is 13204687.

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

It is a cyclic number.

It is not a de Polignac number, because 78640231 - 2¹ = 78640229 is a prime.

It is a super-2 number, since 2×78640231² = 12368571863466722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 78640193 and 78640202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78640271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1606 + ... + 12643.

It is an arithmetic number, because the mean of its divisors is an integer number (19665000).

Almost surely, 2^78640231 is an apocalyptic number.

78640231 is a deficient number, since it is larger than the sum of its proper divisors (19769).

78640231 is a wasteful number, since it uses less digits than its factorization.

78640231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19768.

The product of its (nonzero) digits is 8064, while the sum is 31.

The square root of 78640231 is about 8867.9327354237. The cubic root of 78640231 is about 428.4316964200.

The spelling of 78640231 in words is "seventy-eight million, six hundred forty thousand, two hundred thirty-one".