687745129121 has 12 divisors (see below), whose sum is σ = 725882774292. Its totient is φ = 651516221664.

The previous prime is 687745129111. The next prime is 687745129177. The reversal of 687745129121 is 121921547786.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 78859872400 + 608885256721 = 280820^2 + 780311^2 .

It is not a de Polignac number, because 687745129121 - 2³⁸ = 412867222177 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (687745129111) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10976735 + ... + 11039211.

It is an arithmetic number, because the mean of its divisors is an integer number (60490231191).

Almost surely, 2^687745129121 is an apocalyptic number.

It is an amenable number.

687745129121 is a deficient number, since it is larger than the sum of its proper divisors (38137645171).

687745129121 is a wasteful number, since it uses less digits than its factorization.

687745129121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93008 (or 92989 counting only the distinct ones).

The product of its digits is 1693440, while the sum is 53.

The spelling of 687745129121 in words is "six hundred eighty-seven billion, seven hundred forty-five million, one hundred twenty-nine thousand, one hundred twenty-one".