256047021 has 16 divisors (see below), whose sum is σ = 399294400. Its totient is φ = 161713584.

The previous prime is 256046981. The next prime is 256047031. The reversal of 256047021 is 120740652.

It is not a de Polignac number, because 256047021 - 2¹⁰ = 256045997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256047031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 249046 + ... + 250071.

It is an arithmetic number, because the mean of its divisors is an integer number (24955900).

Almost surely, 2^256047021 is an apocalyptic number.

It is an amenable number.

256047021 is a deficient number, since it is larger than the sum of its proper divisors (143247379).

256047021 is a wasteful number, since it uses less digits than its factorization.

256047021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499145 (or 499139 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 256047021 is about 16001.4693387826. The cubic root of 256047021 is about 634.9992940245. Note that the first 3 decimals are identical.

Adding to 256047021 its reverse (120740652), we get a palindrome (376787673).

The spelling of 256047021 in words is "two hundred fifty-six million, forty-seven thousand, twenty-one".