256635397 has 2 divisors, whose sum is σ = 256635398. Its totient is φ = 256635396.

The previous prime is 256635361. The next prime is 256635409. The reversal of 256635397 is 793536652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 171976996 + 84658401 = 13114^2 + 9201^2 .

It is a cyclic number.

It is not a de Polignac number, because 256635397 - 2¹⁹ = 256111109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256635347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128317698 + 128317699.

It is an arithmetic number, because the mean of its divisors is an integer number (128317699).

Almost surely, 2^256635397 is an apocalyptic number.

It is an amenable number.

256635397 is a deficient number, since it is larger than the sum of its proper divisors (1).

256635397 is an equidigital number, since it uses as much as digits as its factorization.

256635397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1020600, while the sum is 46.

The square root of 256635397 is about 16019.8438506747. The cubic root of 256635397 is about 635.4853148161.

The spelling of 256635397 in words is "two hundred fifty-six million, six hundred thirty-five thousand, three hundred ninety-seven".