21123120221 has 8 divisors (see below), whose sum is σ = 24145208640. Its totient is φ = 18102156768.

The previous prime is 21123120209. The next prime is 21123120229. The reversal of 21123120221 is 12202132112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21123120221 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21123120221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123120229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 240611 + ... + 316448.

It is an arithmetic number, because the mean of its divisors is an integer number (3018151080).

Almost surely, 2^21123120221 is an apocalyptic number.

It is an amenable number.

21123120221 is a deficient number, since it is larger than the sum of its proper divisors (3022088419).

21123120221 is an equidigital number, since it uses as much as digits as its factorization.

21123120221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562483.

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

Adding to 21123120221 its reverse (12202132112), we get a palindrome (33325252333).

The spelling of 21123120221 in words is "twenty-one billion, one hundred twenty-three million, one hundred twenty thousand, two hundred twenty-one".