400640121 has 32 divisors (see below), whose sum is σ = 692192000. Its totient is φ = 228931920.

The previous prime is 400640113. The next prime is 400640153. The reversal of 400640121 is 121046004.

400640121 is a `hidden beast` number, since 4 + 0 + 0 + 640 + 1 + 21 = 666.

It is not a de Polignac number, because 400640121 - 2³ = 400640113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 400640094 and 400640103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400640111) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12370 + ... + 30891.

It is an arithmetic number, because the mean of its divisors is an integer number (21631000).

Almost surely, 2^400640121 is an apocalyptic number.

It is an amenable number.

400640121 is a deficient number, since it is larger than the sum of its proper divisors (291551879).

400640121 is an equidigital number, since it uses as much as digits as its factorization.

400640121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43291 (or 43271 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 400640121 is about 20015.9966276976. The cubic root of 400640121 is about 737.1991279091.

Adding to 400640121 its reverse (121046004), we get a palindrome (521686125).

The spelling of 400640121 in words is "four hundred million, six hundred forty thousand, one hundred twenty-one".