20123440021 has 4 divisors (see below), whose sum is σ = 20132885344. Its totient is φ = 20113994700.

The previous prime is 20123440013. The next prime is 20123440033. The reversal of 20123440021 is 12004432102.

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 20123440021 - 2³ = 20123440013 is a prime.

It is a super-3 number, since 3×20123440021³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20123440061) 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, 4719465 + ... + 4723726.

It is an arithmetic number, because the mean of its divisors is an integer number (5033221336).

Almost surely, 2^20123440021 is an apocalyptic number.

It is an amenable number.

20123440021 is a deficient number, since it is larger than the sum of its proper divisors (9445323).

20123440021 is an equidigital number, since it uses as much as digits as its factorization.

20123440021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9445322.

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

Adding to 20123440021 its reverse (12004432102), we get a palindrome (32127872123).

The spelling of 20123440021 in words is "twenty billion, one hundred twenty-three million, four hundred forty thousand, twenty-one".