20406121 has 4 divisors (see below), whose sum is σ = 20519044. Its totient is φ = 20293200.

The previous prime is 20406119. The next prime is 20406143. The reversal of 20406121 is 12160402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12160402 = 2 ⋅6080201.

It can be written as a sum of positive squares in 2 ways, for example, as 3759721 + 16646400 = 1939^2 + 4080^2 .

It is a cyclic number.

It is not a de Polignac number, because 20406121 - 2¹ = 20406119 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20406095 and 20406104.

It is not an unprimeable number, because it can be changed into a prime (20406161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56190 + ... + 56551.

It is an arithmetic number, because the mean of its divisors is an integer number (5129761).

Almost surely, 2^20406121 is an apocalyptic number.

It is an amenable number.

20406121 is a deficient number, since it is larger than the sum of its proper divisors (112923).

20406121 is a wasteful number, since it uses less digits than its factorization.

20406121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112922.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 20406121 is about 4517.3134715226. The cubic root of 20406121 is about 273.2667672855.

Adding to 20406121 its reverse (12160402), we get a palindrome (32566523).

The spelling of 20406121 in words is "twenty million, four hundred six thousand, one hundred twenty-one".