688727581 has 2 divisors, whose sum is σ = 688727582. Its totient is φ = 688727580.

The previous prime is 688727573. The next prime is 688727587. The reversal of 688727581 is 185727886.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 561263481 + 127464100 = 23691^2 + 11290^2 .

It is a cyclic number.

It is not a de Polignac number, because 688727581 - 2³ = 688727573 is a prime.

It is a super-2 number, since 2×688727581² = 948691361660223122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (688727587) 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, 344363790 + 344363791.

It is an arithmetic number, because the mean of its divisors is an integer number (344363791).

Almost surely, 2^688727581 is an apocalyptic number.

It is an amenable number.

688727581 is a deficient number, since it is larger than the sum of its proper divisors (1).

688727581 is an equidigital number, since it uses as much as digits as its factorization.

688727581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1505280, while the sum is 52.

The square root of 688727581 is about 26243.6198151093. The cubic root of 688727581 is about 883.1120791848.

The spelling of 688727581 in words is "six hundred eighty-eight million, seven hundred twenty-seven thousand, five hundred eighty-one".