400121 has 4 divisors (see below), whose sum is σ = 421200. Its totient is φ = 379044.

The previous prime is 400109. The next prime is 400123. The reversal of 400121 is 121004.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 400121 - 2¹⁰ = 399097 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 400099 and 400108.

It is not an unprimeable number, because it can be changed into a prime (400123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10511 + ... + 10548.

It is an arithmetic number, because the mean of its divisors is an integer number (105300).

2⁴⁰⁰¹²¹ is an apocalyptic number.

It is an amenable number.

400121 is a deficient number, since it is larger than the sum of its proper divisors (21079).

400121 is a wasteful number, since it uses less digits than its factorization.

400121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21078.

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 400121 is about 632.5511836998. The cubic root of 400121 is about 73.6880586873.

Adding to 400121 its reverse (121004), we get a palindrome (521125).

It can be divided in two parts, 400 and 121, that multiplied together give a square (48400 = 220²).

The spelling of 400121 in words is "four hundred thousand, one hundred twenty-one", and thus it is an iban number.