21004131121 has 8 divisors (see below), whose sum is σ = 21522134088. Its totient is φ = 20486400000.

The previous prime is 21004131119. The next prime is 21004131131. The reversal of 21004131121 is 12113140012.

It can be written as a sum of positive squares in 4 ways, for example, as 3713196096 + 17290935025 = 60936^2 + 131495^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21004131121 - 2¹ = 21004131119 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21004131095 and 21004131104.

It is not an unprimeable number, because it can be changed into a prime (21004131131) 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 7 ways as a sum of consecutive naturals, for example, 93121 + ... + 225121.

It is an arithmetic number, because the mean of its divisors is an integer number (2690266761).

Almost surely, 2^21004131121 is an apocalyptic number.

It is an amenable number.

21004131121 is a deficient number, since it is larger than the sum of its proper divisors (518002967).

21004131121 is a wasteful number, since it uses less digits than its factorization.

21004131121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135923.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21004131121 its reverse (12113140012), we get a palindrome (33117271133).

The spelling of 21004131121 in words is "twenty-one billion, four million, one hundred thirty-one thousand, one hundred twenty-one".