78431831 has 4 divisors (see below), whose sum is σ = 79126032. Its totient is φ = 77737632.

The previous prime is 78431819. The next prime is 78431833. The reversal of 78431831 is 13813487.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78431831 is a prime.

It is a super-2 number, since 2×78431831² = 12303104228025122, 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 = 78431791 and 78431800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78431833) 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, 346931 + ... + 347156.

It is an arithmetic number, because the mean of its divisors is an integer number (19781508).

Almost surely, 2^78431831 is an apocalyptic number.

78431831 is a deficient number, since it is larger than the sum of its proper divisors (694201).

78431831 is a wasteful number, since it uses less digits than its factorization.

78431831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694200.

The product of its digits is 16128, while the sum is 35.

The square root of 78431831 is about 8856.1747385652. The cubic root of 78431831 is about 428.0529074695.

The spelling of 78431831 in words is "seventy-eight million, four hundred thirty-one thousand, eight hundred thirty-one".