687990749257 has 32 divisors (see below), whose sum is σ = 808608568320. Its totient is φ = 573071915520.

The previous prime is 687990749213. The next prime is 687990749269. The reversal of 687990749257 is 752947099786.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-687990749257 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 687990749257.

It is not an unprimeable number, because it can be changed into a prime (687990749657) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 184594528 + ... + 184598254.

It is an arithmetic number, because the mean of its divisors is an integer number (25269017760).

Almost surely, 2^687990749257 is an apocalyptic number.

It is an amenable number.

687990749257 is a deficient number, since it is larger than the sum of its proper divisors (120617819063).

687990749257 is a wasteful number, since it uses less digits than its factorization.

687990749257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6121.

The product of its (nonzero) digits is 480090240, while the sum is 73.

The spelling of 687990749257 in words is "six hundred eighty-seven billion, nine hundred ninety million, seven hundred forty-nine thousand, two hundred fifty-seven".