21123120001 has 4 divisors (see below), whose sum is σ = 21166141104. Its totient is φ = 21080098900.

The previous prime is 21123119999. The next prime is 21123120017. The reversal of 21123120001 is 10002132112.

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 a cyclic number.

It is not a de Polignac number, because 21123120001 - 2¹ = 21123119999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123121001) 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, 21509815 + ... + 21510796.

It is an arithmetic number, because the mean of its divisors is an integer number (5291535276).

Almost surely, 2^21123120001 is an apocalyptic number.

It is an amenable number.

21123120001 is a deficient number, since it is larger than the sum of its proper divisors (43021103).

21123120001 is an equidigital number, since it uses as much as digits as its factorization.

21123120001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43021102.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21123120001 its reverse (10002132112), we get a palindrome (31125252113).

The spelling of 21123120001 in words is "twenty-one billion, one hundred twenty-three million, one hundred twenty thousand, one".