221655491 has 2 divisors, whose sum is σ = 221655492. Its totient is φ = 221655490.

The previous prime is 221655461. The next prime is 221655523. The reversal of 221655491 is 194556122.

It is a happy number.

221655491 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221655491 - 2¹⁴ = 221639107 is a prime.

It is not a weakly prime, because it can be changed into another prime (221655461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110827745 + 110827746.

It is an arithmetic number, because the mean of its divisors is an integer number (110827746).

Almost surely, 2^221655491 is an apocalyptic number.

221655491 is a deficient number, since it is larger than the sum of its proper divisors (1).

221655491 is an equidigital number, since it uses as much as digits as its factorization.

221655491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21600, while the sum is 35.

The square root of 221655491 is about 14888.0989719977. The cubic root of 221655491 is about 605.1915164460.

The spelling of 221655491 in words is "two hundred twenty-one million, six hundred fifty-five thousand, four hundred ninety-one".