21011001123 has 16 divisors (see below), whose sum is σ = 32346836480. Its totient is φ = 11882509056.

The previous prime is 21011001083. The next prime is 21011001127. The reversal of 21011001123 is 32110011012.

It is not a de Polignac number, because 21011001123 - 2¹⁰ = 21011000099 is a prime.

It is a super-2 number, since 2×21011001123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21011001099 and 21011001108.

It is not an unprimeable number, because it can be changed into a prime (21011001127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5155303 + ... + 5159376.

It is an arithmetic number, because the mean of its divisors is an integer number (2021677280).

Almost surely, 2^21011001123 is an apocalyptic number.

21011001123 is a deficient number, since it is larger than the sum of its proper divisors (11335835357).

21011001123 is a wasteful number, since it uses less digits than its factorization.

21011001123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10314786.

The product of its (nonzero) digits is 12, while the sum is 12.

Adding to 21011001123 its reverse (32110011012), we get a palindrome (53121012135).

The spelling of 21011001123 in words is "twenty-one billion, eleven million, one thousand, one hundred twenty-three".