221665363207421 has 32 divisors (see below), whose sum is σ = 264378869913600. Its totient is φ = 181835776140480.

The previous prime is 221665363207333. The next prime is 221665363207433. The reversal of 221665363207421 is 124702363566122.

It is a de Polignac number, because none of the positive numbers 2^k-221665363207421 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 221665363207421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221665363207121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1493306 + ... + 21108308.

It is an arithmetic number, because the mean of its divisors is an integer number (8261839684800).

Almost surely, 2^{221665363207421} is an apocalyptic number.

It is an amenable number.

221665363207421 is a deficient number, since it is larger than the sum of its proper divisors (42713506706179).

221665363207421 is a wasteful number, since it uses less digits than its factorization.

221665363207421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19615529.

The product of its (nonzero) digits is 4354560, while the sum is 50.

The spelling of 221665363207421 in words is "two hundred twenty-one trillion, six hundred sixty-five billion, three hundred sixty-three million, two hundred seven thousand, four hundred twenty-one".