400121001 has 12 divisors (see below), whose sum is σ = 660517312. Its totient is φ = 228640536.

The previous prime is 400120991. The next prime is 400121003. The reversal of 400121001 is 100121004.

It is a happy number.

It is not a de Polignac number, because 400121001 - 2⁵ = 400120969 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (400121003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3175501 + ... + 3175626.

Almost surely, 2^400121001 is an apocalyptic number.

It is an amenable number.

400121001 is a deficient number, since it is larger than the sum of its proper divisors (260396311).

400121001 is a wasteful number, since it uses less digits than its factorization.

400121001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6351140 (or 6351137 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 400121001 is about 20003.0247962652. The cubic root of 400121001 is about 736.8805874871.

Adding to 400121001 its reverse (100121004), we get a palindrome (500242005).

The spelling of 400121001 in words is "four hundred million, one hundred twenty-one thousand, one".