21221012123 has 4 divisors (see below), whose sum is σ = 22143664848. Its totient is φ = 20298359400.

The previous prime is 21221012119. The next prime is 21221012177. The reversal of 21221012123 is 32121012212.

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 21221012123 - 2² = 21221012119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221012623) 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, 461326328 + ... + 461326373.

It is an arithmetic number, because the mean of its divisors is an integer number (5535916212).

Almost surely, 2^21221012123 is an apocalyptic number.

21221012123 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21221012123 is a deficient number, since it is larger than the sum of its proper divisors (922652725).

21221012123 is an equidigital number, since it uses as much as digits as its factorization.

21221012123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 922652724.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21221012123 its reverse (32121012212), we get a palindrome (53342024335).

The spelling of 21221012123 in words is "twenty-one billion, two hundred twenty-one million, twelve thousand, one hundred twenty-three".