688531 has 2 divisors, whose sum is σ = 688532. Its totient is φ = 688530.

The previous prime is 688511. The next prime is 688543. The reversal of 688531 is 135886.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 688531 - 2⁷ = 688403 is a prime.

It is a super-2 number, since 2×688531² = 948149875922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 688493 and 688502.

It is not a weakly prime, because it can be changed into another prime (688511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344265 + 344266.

It is an arithmetic number, because the mean of its divisors is an integer number (344266).

2⁶⁸⁸⁵³¹ is an apocalyptic number.

688531 is a deficient number, since it is larger than the sum of its proper divisors (1).

688531 is an equidigital number, since it uses as much as digits as its factorization.

688531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 31.

The square root of 688531 is about 829.7776810689. Note that the first 3 decimals coincide. The cubic root of 688531 is about 88.3028050037.

The spelling of 688531 in words is "six hundred eighty-eight thousand, five hundred thirty-one".