221666351640 has 64 divisors (see below), whose sum is σ = 671854750560. Its totient is φ = 58501632000.

The previous prime is 221666351633. The next prime is 221666351681. The reversal of 221666351640 is 46153666122.

It is a junction number, because it is equal to n+sod(n) for n = 221666351592 and 221666351601.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9510111 + ... + 9533390.

Almost surely, 2^221666351640 is an apocalyptic number.

221666351640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

221666351640 is an abundant number, since it is smaller than the sum of its proper divisors (450188398920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221666351640 is a wasteful number, since it uses less digits than its factorization.

221666351640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19043612 (or 19043608 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 42.

The spelling of 221666351640 in words is "two hundred twenty-one billion, six hundred sixty-six million, three hundred fifty-one thousand, six hundred forty".