688400249 has 2 divisors, whose sum is σ = 688400250. Its totient is φ = 688400248.

The previous prime is 688400243. The next prime is 688400269. The reversal of 688400249 is 942004886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 358723600 + 329676649 = 18940^2 + 18157^2 .

It is a cyclic number.

It is not a de Polignac number, because 688400249 - 2²⁰ = 687351673 is a prime.

It is not a weakly prime, because it can be changed into another prime (688400243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344200124 + 344200125.

It is an arithmetic number, because the mean of its divisors is an integer number (344200125).

Almost surely, 2^688400249 is an apocalyptic number.

It is an amenable number.

688400249 is a deficient number, since it is larger than the sum of its proper divisors (1).

688400249 is an equidigital number, since it uses as much as digits as its factorization.

688400249 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 110592, while the sum is 41.

The square root of 688400249 is about 26237.3826629106. The cubic root of 688400249 is about 882.9721512661.

The spelling of 688400249 in words is "six hundred eighty-eight million, four hundred thousand, two hundred forty-nine".