404551855721 has 4 divisors (see below), whose sum is σ = 435671229252. Its totient is φ = 373432482192.

The previous prime is 404551855717. The next prime is 404551855751. The reversal of 404551855721 is 127558155404.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 240173505625 + 164378350096 = 490075^2 + 405436^2 .

It is a cyclic number.

It is not a de Polignac number, because 404551855721 - 2² = 404551855717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (404551855751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15559686746 + ... + 15559686771.

It is an arithmetic number, because the mean of its divisors is an integer number (108917807313).

Almost surely, 2^404551855721 is an apocalyptic number.

It is an amenable number.

404551855721 is a deficient number, since it is larger than the sum of its proper divisors (31119373531).

404551855721 is a wasteful number, since it uses less digits than its factorization.

404551855721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31119373530.

The product of its (nonzero) digits is 1120000, while the sum is 47.

The spelling of 404551855721 in words is "four hundred four billion, five hundred fifty-one million, eight hundred fifty-five thousand, seven hundred twenty-one".