21020134121 has 24 divisors (see below), whose sum is σ = 25127636040. Its totient is φ = 17519991552.

The previous prime is 21020134099. The next prime is 21020134123. The reversal of 21020134121 is 12143102012.

It can be written as a sum of positive squares in 4 ways, for example, as 1508234896 + 19511899225 = 38836^2 + 139685^2 .

It is not a de Polignac number, because 21020134121 - 2¹⁰ = 21020133097 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21020134121.

It is not an unprimeable number, because it can be changed into a prime (21020134123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5816111 + ... + 5819723.

It is an arithmetic number, because the mean of its divisors is an integer number (1046984835).

Almost surely, 2^21020134121 is an apocalyptic number.

It is an amenable number.

21020134121 is a deficient number, since it is larger than the sum of its proper divisors (4107501919).

21020134121 is a wasteful number, since it uses less digits than its factorization.

21020134121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6873 (or 6866 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21020134121 its reverse (12143102012), we get a palindrome (33163236133).

The spelling of 21020134121 in words is "twenty-one billion, twenty million, one hundred thirty-four thousand, one hundred twenty-one".