21420344433 has 4 divisors (see below), whose sum is σ = 28560459248. Its totient is φ = 14280229620.

The previous prime is 21420344419. The next prime is 21420344453. The reversal of 21420344433 is 33444302412.

It is a happy number.

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 not a de Polignac number, because 21420344433 - 2⁴ = 21420344417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21420344433.

It is not an unprimeable number, because it can be changed into a prime (21420344453) 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, 3570057403 + ... + 3570057408.

It is an arithmetic number, because the mean of its divisors is an integer number (7140114812).

Almost surely, 2^21420344433 is an apocalyptic number.

It is an amenable number.

21420344433 is a deficient number, since it is larger than the sum of its proper divisors (7140114815).

21420344433 is an equidigital number, since it uses as much as digits as its factorization.

21420344433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7140114814.

The product of its (nonzero) digits is 27648, while the sum is 30.

Adding to 21420344433 its reverse (33444302412), we get a palindrome (54864646845).

The spelling of 21420344433 in words is "twenty-one billion, four hundred twenty million, three hundred forty-four thousand, four hundred thirty-three".