21420022123 has 4 divisors (see below), whose sum is σ = 21423824968. Its totient is φ = 21416219280.

The previous prime is 21420022121. The next prime is 21420022147. The reversal of 21420022123 is 32122002412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21420022123 - 2¹ = 21420022121 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21420022123.

It is not an unprimeable number, because it can be changed into a prime (21420022121) 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, 1892961 + ... + 1904242.

It is an arithmetic number, because the mean of its divisors is an integer number (5355956242).

Almost surely, 2^21420022123 is an apocalyptic number.

21420022123 is a deficient number, since it is larger than the sum of its proper divisors (3802845).

21420022123 is an equidigital number, since it uses as much as digits as its factorization.

21420022123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3802844.

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

Adding to 21420022123 its reverse (32122002412), we get a palindrome (53542024535).

The spelling of 21420022123 in words is "twenty-one billion, four hundred twenty million, twenty-two thousand, one hundred twenty-three".