400001777721 has 48 divisors (see below), whose sum is σ = 735635496960. Its totient is φ = 203714421120.

The previous prime is 400001777657. The next prime is 400001777723. The reversal of 400001777721 is 127777100004.

It is not a de Polignac number, because 400001777721 - 2⁶ = 400001777657 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (400001777723) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 8396985 + ... + 8444486.

It is an arithmetic number, because the mean of its divisors is an integer number (15325739520).

Almost surely, 2^400001777721 is an apocalyptic number.

It is an amenable number.

400001777721 is a deficient number, since it is larger than the sum of its proper divisors (335633719239).

400001777721 is a wasteful number, since it uses less digits than its factorization.

400001777721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16841526 (or 16841523 counting only the distinct ones).

The product of its (nonzero) digits is 19208, while the sum is 36.

Adding to 400001777721 its reverse (127777100004), we get a palindrome (527778877725).

The spelling of 400001777721 in words is "four hundred billion, one million, seven hundred seventy-seven thousand, seven hundred twenty-one".