257720660 has 24 divisors (see below), whose sum is σ = 548630376. Its totient is φ = 101675520.

The previous prime is 257720653. The next prime is 257720677. The reversal of 257720660 is 66027752.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 112614544 + 145106116 = 10612^2 + 12046^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 257720660.

It is a congruent number.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 86801 + ... + 89720.

It is an arithmetic number, because the mean of its divisors is an integer number (22859599).

Almost surely, 2^257720660 is an apocalyptic number.

257720660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

257720660 is an abundant number, since it is smaller than the sum of its proper divisors (290909716).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

257720660 is a wasteful number, since it uses less digits than its factorization.

257720660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176603 (or 176601 counting only the distinct ones).

The product of its (nonzero) digits is 35280, while the sum is 35.

The square root of 257720660 is about 16053.6805748713. The cubic root of 257720660 is about 636.3798378435.

The spelling of 257720660 in words is "two hundred fifty-seven million, seven hundred twenty thousand, six hundred sixty".