216642942721 has 4 divisors (see below), whose sum is σ = 229386645252. Its totient is φ = 203899240192.

The previous prime is 216642942701. The next prime is 216642942727. The reversal of 216642942721 is 127249246612.

216642942721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 199151557696 + 17491385025 = 446264^2 + 132255^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216642942721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216642942727) 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 3 ways as a sum of consecutive naturals, for example, 6371851240 + ... + 6371851273.

It is an arithmetic number, because the mean of its divisors is an integer number (57346661313).

Almost surely, 2^216642942721 is an apocalyptic number.

It is an amenable number.

216642942721 is a deficient number, since it is larger than the sum of its proper divisors (12743702531).

216642942721 is a wasteful number, since it uses less digits than its factorization.

216642942721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12743702530.

The product of its digits is 580608, while the sum is 46.

The spelling of 216642942721 in words is "two hundred sixteen billion, six hundred forty-two million, nine hundred forty-two thousand, seven hundred twenty-one".