221642621648781 has 16 divisors (see below), whose sum is σ = 296107516797120. Its totient is φ = 147469743850880.

The previous prime is 221642621648687. The next prime is 221642621648827. The reversal of 221642621648781 is 187846126246122.

It is a cyclic number.

It is not a de Polignac number, because 221642621648781 - 2¹⁰ = 221642621647757 is a prime.

It is a super-2 number, since 2×221642621648781² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221642621698781) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 138824446 + ... + 140411936.

It is an arithmetic number, because the mean of its divisors is an integer number (18506719799820).

Almost surely, 2^{221642621648781} is an apocalyptic number.

It is an amenable number.

221642621648781 is a deficient number, since it is larger than the sum of its proper divisors (74464895148339).

221642621648781 is a wasteful number, since it uses less digits than its factorization.

221642621648781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1679436.

The product of its digits is 24772608, while the sum is 60.

The spelling of 221642621648781 in words is "two hundred twenty-one trillion, six hundred forty-two billion, six hundred twenty-one million, six hundred forty-eight thousand, seven hundred eighty-one".