21423220420 has 36 divisors (see below), whose sum is σ = 52333869420. Its totient is φ = 7345103808.

The previous prime is 21423220369. The next prime is 21423220421. The reversal of 21423220420 is 2402232412.

It can be written as a sum of positive squares in 2 ways, for example, as 16277166724 + 5146053696 = 127582^2 + 71736^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21423220391 and 21423220400.

It is not an unprimeable number, because it can be changed into a prime (21423220421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10929235 + ... + 10931194.

It is an arithmetic number, because the mean of its divisors is an integer number (1453718595).

Almost surely, 2^21423220420 is an apocalyptic number.

21423220420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21423220420 is an abundant number, since it is smaller than the sum of its proper divisors (30910649000).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21423220420 is a wasteful number, since it uses less digits than its factorization.

21423220420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21860452 (or 21860443 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

Adding to 21423220420 its reverse (2402232412), we get a palindrome (23825452832).

The spelling of 21423220420 in words is "twenty-one billion, four hundred twenty-three million, two hundred twenty thousand, four hundred twenty".