21123302121 has 8 divisors (see below), whose sum is σ = 31293780960. Its totient is φ = 14082201396.

The previous prime is 21123302107. The next prime is 21123302191. The reversal of 21123302121 is 12120332112.

21123302121 is a `hidden beast` number, since 211 + 2 + 330 + 2 + 121 = 666.

It is not a de Polignac number, because 21123302121 - 2⁷ = 21123301993 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21123302094 and 21123302103.

It is not an unprimeable number, because it can be changed into a prime (21123302191) 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, 391172235 + ... + 391172288.

It is an arithmetic number, because the mean of its divisors is an integer number (3911722620).

Almost surely, 2^21123302121 is an apocalyptic number.

It is an amenable number.

21123302121 is a deficient number, since it is larger than the sum of its proper divisors (10170478839).

21123302121 is an equidigital number, since it uses as much as digits as its factorization.

21123302121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 782344532 (or 782344526 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21123302121 its reverse (12120332112), we get a palindrome (33243634233).

The spelling of 21123302121 in words is "twenty-one billion, one hundred twenty-three million, three hundred two thousand, one hundred twenty-one".