20402232121 has 4 divisors (see below), whose sum is σ = 20406410100. Its totient is φ = 20398054144.

The previous prime is 20402232031. The next prime is 20402232143. The reversal of 20402232121 is 12123220402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12123220402 = 2 ⋅6061610201.

It can be written as a sum of positive squares in 2 ways, for example, as 17479748521 + 2922483600 = 132211^2 + 54060^2 .

It is a cyclic number.

It is not a de Polignac number, because 20402232121 - 2⁹ = 20402231609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20402236121) 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, 2081656 + ... + 2091433.

It is an arithmetic number, because the mean of its divisors is an integer number (5101602525).

Almost surely, 2^20402232121 is an apocalyptic number.

It is an amenable number.

20402232121 is a deficient number, since it is larger than the sum of its proper divisors (4177979).

20402232121 is an equidigital number, since it uses as much as digits as its factorization.

20402232121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4177978.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 20402232121 its reverse (12123220402), we get a palindrome (32525452523).

The spelling of 20402232121 in words is "twenty billion, four hundred two million, two hundred thirty-two thousand, one hundred twenty-one".