21301557532721 has 4 divisors (see below), whose sum is σ = 21302577792000. Its totient is φ = 21300537273444.

The previous prime is 21301557532691. The next prime is 21301557532733. The reversal of 21301557532721 is 12723575510312.

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 a de Polignac number, because none of the positive numbers 2^k-21301557532721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21301557532781) 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, 510098321 + ... + 510140078.

It is an arithmetic number, because the mean of its divisors is an integer number (5325644448000).

Almost surely, 2^{21301557532721} is an apocalyptic number.

It is an amenable number.

21301557532721 is a deficient number, since it is larger than the sum of its proper divisors (1020259279).

21301557532721 is a wasteful number, since it uses less digits than its factorization.

21301557532721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1020259278.

The product of its (nonzero) digits is 441000, while the sum is 44.

The spelling of 21301557532721 in words is "twenty-one trillion, three hundred one billion, five hundred fifty-seven million, five hundred thirty-two thousand, seven hundred twenty-one".