21001330123 has 4 divisors (see below), whose sum is σ = 21012702480. Its totient is φ = 20989957768.

The previous prime is 21001330111. The next prime is 21001330157. The reversal of 21001330123 is 32103310012.

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 21001330123 - 2²¹ = 20999232971 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001330097 and 21001330106.

It is not an unprimeable number, because it can be changed into a prime (21001333123) 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, 5683408 + ... + 5687101.

It is an arithmetic number, because the mean of its divisors is an integer number (5253175620).

Almost surely, 2^21001330123 is an apocalyptic number.

21001330123 is a deficient number, since it is larger than the sum of its proper divisors (11372357).

21001330123 is a wasteful number, since it uses less digits than its factorization.

21001330123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11372356.

The product of its (nonzero) digits is 108, while the sum is 16.

Adding to 21001330123 its reverse (32103310012), we get a palindrome (53104640135).

The spelling of 21001330123 in words is "twenty-one billion, one million, three hundred thirty thousand, one hundred twenty-three".