21221230123 has 4 divisors (see below), whose sum is σ = 21226864360. Its totient is φ = 21215595888.

The previous prime is 21221230109. The next prime is 21221230127. The reversal of 21221230123 is 32103212212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221230123 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 21221230123.

It is not an unprimeable number, because it can be changed into a prime (21221230127) 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, 2811465 + ... + 2819002.

It is an arithmetic number, because the mean of its divisors is an integer number (5306716090).

Almost surely, 2^21221230123 is an apocalyptic number.

21221230123 is a deficient number, since it is larger than the sum of its proper divisors (5634237).

21221230123 is an equidigital number, since it uses as much as digits as its factorization.

21221230123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5634236.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21221230123 its reverse (32103212212), we get a palindrome (53324442335).

The spelling of 21221230123 in words is "twenty-one billion, two hundred twenty-one million, two hundred thirty thousand, one hundred twenty-three".