688146989 has 2 divisors, whose sum is σ = 688146990. Its totient is φ = 688146988.

The previous prime is 688146971. The next prime is 688147121. The reversal of 688146989 is 989641886.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 540330025 + 147816964 = 23245^2 + 12158^2 .

It is a cyclic number.

It is not a de Polignac number, because 688146989 - 2⁸ = 688146733 is a prime.

It is a super-2 number, since 2×688146989² = 947092556939532242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688146919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344073494 + 344073495.

It is an arithmetic number, because the mean of its divisors is an integer number (344073495).

Almost surely, 2^688146989 is an apocalyptic number.

It is an amenable number.

688146989 is a deficient number, since it is larger than the sum of its proper divisors (1).

688146989 is an equidigital number, since it uses as much as digits as its factorization.

688146989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5971968, while the sum is 59.

The square root of 688146989 is about 26232.5558991113. Note that the first 3 decimals coincide. The cubic root of 688146989 is about 882.8638572147.

The spelling of 688146989 in words is "six hundred eighty-eight million, one hundred forty-six thousand, nine hundred eighty-nine".