687431 has 2 divisors, whose sum is σ = 687432. Its totient is φ = 687430.

The previous prime is 687413. The next prime is 687433. The reversal of 687431 is 134786.

Together with previous prime (687413) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687431 is a prime.

It is a super-2 number, since 2×687431² = 945122759522, which contains 22 as substring.

Together with 687433, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 687394 and 687403.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343715 + 343716.

It is an arithmetic number, because the mean of its divisors is an integer number (343716).

2⁶⁸⁷⁴³¹ is an apocalyptic number.

687431 is a deficient number, since it is larger than the sum of its proper divisors (1).

687431 is an equidigital number, since it uses as much as digits as its factorization.

687431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 29.

The square root of 687431 is about 829.1145879792. The cubic root of 687431 is about 88.2557556294.

The spelling of 687431 in words is "six hundred eighty-seven thousand, four hundred thirty-one".