21506730621121 has 4 divisors (see below), whose sum is σ = 21526443482544. Its totient is φ = 21487017759700.

The previous prime is 21506730621043. The next prime is 21506730621161. The reversal of 21506730621121 is 12112603760512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21506730621121 - 2³¹ = 21504583137473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21506730621161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9856429075 + ... + 9856431256.

It is an arithmetic number, because the mean of its divisors is an integer number (5381610870636).

Almost surely, 2^{21506730621121} is an apocalyptic number.

It is an amenable number.

21506730621121 is a deficient number, since it is larger than the sum of its proper divisors (19712861423).

21506730621121 is a wasteful number, since it uses less digits than its factorization.

21506730621121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19712861422.

The product of its (nonzero) digits is 30240, while the sum is 37.

The spelling of 21506730621121 in words is "twenty-one trillion, five hundred six billion, seven hundred thirty million, six hundred twenty-one thousand, one hundred twenty-one".