256421242 has 16 divisors (see below), whose sum is σ = 479541312. Its totient is φ = 99904320.

The previous prime is 256421239. The next prime is 256421293. The reversal of 256421242 is 242124652.

It is a self number, because there is not a number n which added to its sum of digits gives 256421242.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 832383 + ... + 832690.

It is an arithmetic number, because the mean of its divisors is an integer number (29971332).

Almost surely, 2^256421242 is an apocalyptic number.

256421242 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

256421242 is a deficient number, since it is larger than the sum of its proper divisors (223120070).

256421242 is a wasteful number, since it uses less digits than its factorization.

256421242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1665093.

The product of its digits is 7680, while the sum is 28.

The square root of 256421242 is about 16013.1584017645. The cubic root of 256421242 is about 635.3085007681.

Adding to 256421242 its reverse (242124652), we get a palindrome (498545894).

The spelling of 256421242 in words is "two hundred fifty-six million, four hundred twenty-one thousand, two hundred forty-two".