256021405 has 32 divisors (see below), whose sum is σ = 326661120. Its totient is φ = 192360960.

The previous prime is 256021393. The next prime is 256021417. The reversal of 256021405 is 504120652.

It is an interprime number because it is at equal distance from previous prime (256021393) and next prime (256021417).

It is not a de Polignac number, because 256021405 - 2⁷ = 256021277 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256021405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 924127 + ... + 924403.

It is an arithmetic number, because the mean of its divisors is an integer number (10208160).

Almost surely, 2^256021405 is an apocalyptic number.

It is an amenable number.

256021405 is a deficient number, since it is larger than the sum of its proper divisors (70639715).

256021405 is a wasteful number, since it uses less digits than its factorization.

256021405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 256021405 is about 16000.6688922682. The cubic root of 256021405 is about 634.9781173355.

The spelling of 256021405 in words is "two hundred fifty-six million, twenty-one thousand, four hundred five".