400020256665 has 12 divisors (see below), whose sum is σ = 693368444964. Its totient is φ = 213344136864.

The previous prime is 400020256651. The next prime is 400020256717. The reversal of 400020256665 is 566652020004.

It can be written as a sum of positive squares in 2 ways, for example, as 49855744656 + 350164512009 = 223284^2 + 591747^2 .

It is not a de Polignac number, because 400020256665 - 2³² = 395725289369 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4444669474 + ... + 4444669563.

It is an arithmetic number, because the mean of its divisors is an integer number (57780703747).

Almost surely, 2^400020256665 is an apocalyptic number.

400020256665 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

400020256665 is a deficient number, since it is larger than the sum of its proper divisors (293348188299).

400020256665 is a wasteful number, since it uses less digits than its factorization.

400020256665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8889339048 (or 8889339045 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

Adding to 400020256665 its reverse (566652020004), we get a palindrome (966672276669).

The spelling of 400020256665 in words is "four hundred billion, twenty million, two hundred fifty-six thousand, six hundred sixty-five".