221386009491 has 12 divisors (see below), whose sum is σ = 331623487832. Its totient is φ = 147590672832.

The previous prime is 221386009391. The next prime is 221386009511. The reversal of 221386009491 is 194900683122.

221386009491 is a `hidden beast` number, since 2 + 2 + 1 + 38 + 600 + 9 + 4 + 9 + 1 = 666.

It is not a de Polignac number, because 221386009491 - 2¹⁵ = 221385976723 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221386009391) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 455526526 + ... + 455527011.

Almost surely, 2^221386009491 is an apocalyptic number.

221386009491 is a deficient number, since it is larger than the sum of its proper divisors (110237478341).

221386009491 is an frugal number, since it uses more digits than its factorization.

221386009491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 911053552 (or 911053540 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The spelling of 221386009491 in words is "two hundred twenty-one billion, three hundred eighty-six million, nine thousand, four hundred ninety-one".