257721047 has 2 divisors, whose sum is σ = 257721048. Its totient is φ = 257721046.

The previous prime is 257721043. The next prime is 257721133. The reversal of 257721047 is 740127752.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 257721047 - 2² = 257721043 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 257720998 and 257721016.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (257721043) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128860523 + 128860524.

It is an arithmetic number, because the mean of its divisors is an integer number (128860524).

Almost surely, 2^257721047 is an apocalyptic number.

257721047 is a deficient number, since it is larger than the sum of its proper divisors (1).

257721047 is an equidigital number, since it uses as much as digits as its factorization.

257721047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27440, while the sum is 35.

The square root of 257721047 is about 16053.6926281775. The cubic root of 257721047 is about 636.3801563782.

Adding to 257721047 its reverse (740127752), we get a palindrome (997848799).

The spelling of 257721047 in words is "two hundred fifty-seven million, seven hundred twenty-one thousand, forty-seven".