221975853661 has 4 divisors (see below), whose sum is σ = 222794953024. Its totient is φ = 221156754300.

The previous prime is 221975853637. The next prime is 221975853667. The reversal of 221975853661 is 166358579122.

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 221975853661 - 2²¹ = 221973756509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221975853667) 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, 409549275 + ... + 409549816.

It is an arithmetic number, because the mean of its divisors is an integer number (55698738256).

Almost surely, 2^221975853661 is an apocalyptic number.

It is an amenable number.

221975853661 is a deficient number, since it is larger than the sum of its proper divisors (819099363).

221975853661 is an equidigital number, since it uses as much as digits as its factorization.

221975853661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 819099362.

The product of its digits is 5443200, while the sum is 55.

The spelling of 221975853661 in words is "two hundred twenty-one billion, nine hundred seventy-five million, eight hundred fifty-three thousand, six hundred sixty-one".