256002021 has 24 divisors (see below), whose sum is σ = 408934656. Its totient is φ = 153023040.

The previous prime is 256002013. The next prime is 256002037. The reversal of 256002021 is 120200652.

256002021 is a `hidden beast` number, since 25 + 600 + 20 + 21 = 666.

It is not a de Polignac number, because 256002021 - 2³ = 256002013 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 256001985 and 256002003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256002821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10485 + ... + 24938.

It is an arithmetic number, because the mean of its divisors is an integer number (17038944).

Almost surely, 2^256002021 is an apocalyptic number.

It is an amenable number.

256002021 is a deficient number, since it is larger than the sum of its proper divisors (152932635).

256002021 is a wasteful number, since it uses less digits than its factorization.

256002021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35513 (or 35510 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 256002021 is about 16000.0631561254. The cubic root of 256002021 is about 634.9620916878.

Adding to 256002021 its reverse (120200652), we get a palindrome (376202673).

The spelling of 256002021 in words is "two hundred fifty-six million, two thousand, twenty-one".