257720993 has 8 divisors (see below), whose sum is σ = 261008616. Its totient is φ = 254448000.

The previous prime is 257720987. The next prime is 257721001. The reversal of 257720993 is 399027752.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 143808064 + 113912929 = 11992^2 + 10673^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 257720993 - 2⁴ = 257720977 is a prime.

It is a super-2 number, since 2×257720993² = 132840220465812098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (257720923) 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 in 7 ways as a sum of consecutive naturals, for example, 34253 + ... + 41093.

It is an arithmetic number, because the mean of its divisors is an integer number (32626077).

Almost surely, 2^257720993 is an apocalyptic number.

It is an amenable number.

257720993 is a deficient number, since it is larger than the sum of its proper divisors (3287623).

257720993 is a wasteful number, since it uses less digits than its factorization.

257720993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7315.

The product of its (nonzero) digits is 238140, while the sum is 44.

The square root of 257720993 is about 16053.6909463213. The cubic root of 257720993 is about 636.3801119315.

The spelling of 257720993 in words is "two hundred fifty-seven million, seven hundred twenty thousand, nine hundred ninety-three".