20420440421 has 4 divisors (see below), whose sum is σ = 20426280000. Its totient is φ = 20414600844.

The previous prime is 20420440387. The next prime is 20420440429. The reversal of 20420440421 is 12404402402.

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 a de Polignac number, because none of the positive numbers 2^k-20420440421 is a prime.

It is a super-2 number, since 2×20420440421² (a number of 21 digits) contains 22 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 (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, 2914541 + ... + 2921538.

It is an arithmetic number, because the mean of its divisors is an integer number (5106570000).

Almost surely, 2^20420440421 is an apocalyptic number.

It is an amenable number.

20420440421 is a deficient number, since it is larger than the sum of its proper divisors (5839579).

20420440421 is an equidigital number, since it uses as much as digits as its factorization.

20420440421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5839578.

The product of its (nonzero) digits is 2048, while the sum is 23.

Adding to 20420440421 its reverse (12404402402), we get a palindrome (32824842823).

The spelling of 20420440421 in words is "twenty billion, four hundred twenty million, four hundred forty thousand, four hundred twenty-one".