21001123131 has 8 divisors (see below), whose sum is σ = 28016503104. Its totient is φ = 13993245960.

The previous prime is 21001123109. The next prime is 21001123177. The reversal of 21001123131 is 13132110012.

It is a happy number.

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

It is not a de Polignac number, because 21001123131 - 2¹⁴ = 21001106747 is a prime.

It is a super-2 number, since 2×21001123131² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21001123131.

It is not an unprimeable number, because it can be changed into a prime (21001123531) 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, 1869165 + ... + 1880366.

It is an arithmetic number, because the mean of its divisors is an integer number (3502062888).

Almost surely, 2^21001123131 is an apocalyptic number.

21001123131 is a deficient number, since it is larger than the sum of its proper divisors (7015379973).

21001123131 is a wasteful number, since it uses less digits than its factorization.

21001123131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3751401.

The product of its (nonzero) digits is 36, while the sum is 15.

Adding to 21001123131 its reverse (13132110012), we get a palindrome (34133233143).

The spelling of 21001123131 in words is "twenty-one billion, one million, one hundred twenty-three thousand, one hundred thirty-one".