20400121 has 12 divisors (see below), whose sum is σ = 23836032. Its totient is φ = 17408328.

The previous prime is 20400101. The next prime is 20400151. The reversal of 20400121 is 12100402.

It is not a de Polignac number, because 20400121 - 2⁵ = 20400089 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20400098 and 20400107.

It is not an unprimeable number, because it can be changed into a prime (20400101) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12096 + ... + 13678.

It is an arithmetic number, because the mean of its divisors is an integer number (1986336).

Almost surely, 2^20400121 is an apocalyptic number.

It is an amenable number.

20400121 is a deficient number, since it is larger than the sum of its proper divisors (3435911).

20400121 is a wasteful number, since it uses less digits than its factorization.

20400121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1860 (or 1853 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 20400121 is about 4516.6493111598. The cubic root of 20400121 is about 273.2399818367.

Adding to 20400121 its reverse (12100402), we get a palindrome (32500523).

The spelling of 20400121 in words is "twenty million, four hundred thousand, one hundred twenty-one".