256421213 has 2 divisors, whose sum is σ = 256421214. Its totient is φ = 256421212.

The previous prime is 256421171. The next prime is 256421239. The reversal of 256421213 is 312124652.

It is a happy number.

It is an a-pointer prime, because the next prime (256421239) can be obtained adding 256421213 to its sum of digits (26).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 252587449 + 3833764 = 15893^2 + 1958^2 .

It is a cyclic number.

It is not a de Polignac number, because 256421213 - 2²⁴ = 239643997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256421293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128210606 + 128210607.

It is an arithmetic number, because the mean of its divisors is an integer number (128210607).

Almost surely, 2^256421213 is an apocalyptic number.

It is an amenable number.

256421213 is a deficient number, since it is larger than the sum of its proper divisors (1).

256421213 is an equidigital number, since it uses as much as digits as its factorization.

256421213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2880, while the sum is 26.

The square root of 256421213 is about 16013.1574962591. The cubic root of 256421213 is about 635.3084768180.

Adding to 256421213 its reverse (312124652), we get a palindrome (568545865).

The spelling of 256421213 in words is "two hundred fifty-six million, four hundred twenty-one thousand, two hundred thirteen".