21011121123 has 16 divisors (see below), whose sum is σ = 28586960640. Its totient is φ = 13722969824.

The previous prime is 21011121073. The next prime is 21011121127. The reversal of 21011121123 is 32112111012.

It is a cyclic number.

It is not a de Polignac number, because 21011121123 - 2⁶ = 21011121059 is a prime.

It is a super-2 number, since 2×21011121123² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21011121127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 150711 + ... + 254432.

It is an arithmetic number, because the mean of its divisors is an integer number (1786685040).

Almost surely, 2^21011121123 is an apocalyptic number.

21011121123 is a deficient number, since it is larger than the sum of its proper divisors (7575839517).

21011121123 is a wasteful number, since it uses less digits than its factorization.

21011121123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405498.

The product of its (nonzero) digits is 24, while the sum is 15.

Adding to 21011121123 its reverse (32112111012), we get a palindrome (53123232135).

The spelling of 21011121123 in words is "twenty-one billion, eleven million, one hundred twenty-one thousand, one hundred twenty-three".