256155421 has 2 divisors, whose sum is σ = 256155422. Its totient is φ = 256155420.

The previous prime is 256155373. The next prime is 256155437. The reversal of 256155421 is 124551652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155875225 + 100280196 = 12485^2 + 10014^2 .

It is a cyclic number.

It is not a de Polignac number, because 256155421 - 2⁹ = 256154909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256155451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128077710 + 128077711.

It is an arithmetic number, because the mean of its divisors is an integer number (128077711).

Almost surely, 2^256155421 is an apocalyptic number.

It is an amenable number.

256155421 is a deficient number, since it is larger than the sum of its proper divisors (1).

256155421 is an equidigital number, since it uses as much as digits as its factorization.

256155421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12000, while the sum is 31.

The square root of 256155421 is about 16004.8561693006. The cubic root of 256155421 is about 635.0888924267.

The spelling of 256155421 in words is "two hundred fifty-six million, one hundred fifty-five thousand, four hundred twenty-one".