20420440423 has 4 divisors (see below), whose sum is σ = 20426293368. Its totient is φ = 20414587480.

The previous prime is 20420440387. The next prime is 20420440429. The reversal of 20420440423 is 32404402402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32404402402 = 2 ⋅16202201201.

It is a cyclic number.

It is not a de Polignac number, because 20420440423 - 2²¹ = 20418343271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20420440429) 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, 2921236 + ... + 2928217.

It is an arithmetic number, because the mean of its divisors is an integer number (5106573342).

Almost surely, 2^20420440423 is an apocalyptic number.

20420440423 is a deficient number, since it is larger than the sum of its proper divisors (5852945).

20420440423 is an equidigital number, since it uses as much as digits as its factorization.

20420440423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5852944.

The product of its (nonzero) digits is 6144, while the sum is 25.

Adding to 20420440423 its reverse (32404402402), we get a palindrome (52824842825).

The spelling of 20420440423 in words is "twenty billion, four hundred twenty million, four hundred forty thousand, four hundred twenty-three".