21202121124 has 36 divisors (see below), whose sum is σ = 53824290156. Its totient is φ = 7037038848.

The previous prime is 21202121111. The next prime is 21202121173. The reversal of 21202121124 is 42112120212.

It can be written as a sum of positive squares in 2 ways, for example, as 14440348224 + 6761772900 = 120168^2 + 82230^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21202121097 and 21202121106.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1255449 + ... + 1272224.

It is an arithmetic number, because the mean of its divisors is an integer number (1495119171).

Almost surely, 2^21202121124 is an apocalyptic number.

It is an amenable number.

21202121124 is an abundant number, since it is smaller than the sum of its proper divisors (32622169032).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21202121124 is a wasteful number, since it uses less digits than its factorization.

21202121124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2527916 (or 2527911 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21202121124 its reverse (42112120212), we get a palindrome (63314241336).

The spelling of 21202121124 in words is "twenty-one billion, two hundred two million, one hundred twenty-one thousand, one hundred twenty-four".