256401388 has 6 divisors (see below), whose sum is σ = 448702436. Its totient is φ = 128200692.

The previous prime is 256401347. The next prime is 256401419. The reversal of 256401388 is 883104652.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32050170 + ... + 32050177.

Almost surely, 2^256401388 is an apocalyptic number.

It is an amenable number.

256401388 is a deficient number, since it is larger than the sum of its proper divisors (192301048).

256401388 is a wasteful number, since it uses less digits than its factorization.

256401388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64100351 (or 64100349 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 37.

The square root of 256401388 is about 16012.5384620928. The cubic root of 256401388 is about 635.2921036079.

It can be divided in two parts, 25640 and 1388, that added together give a triangular number (27028 = T₂₃₂).

The spelling of 256401388 in words is "two hundred fifty-six million, four hundred one thousand, three hundred eighty-eight".