221064665 has 4 divisors (see below), whose sum is σ = 265277604. Its totient is φ = 176851728.

The previous prime is 221064653. The next prime is 221064703. The reversal of 221064665 is 566460122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566460122 = 2 ⋅283230061.

It can be written as a sum of positive squares in 2 ways, for example, as 128981449 + 92083216 = 11357^2 + 9596^2 .

It is a cyclic number.

It is not a de Polignac number, because 221064665 - 2¹⁸ = 220802521 is a prime.

It is a super-2 number, since 2×221064665² = 97739172223124450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22106462 + ... + 22106471.

It is an arithmetic number, because the mean of its divisors is an integer number (66319401).

Almost surely, 2^221064665 is an apocalyptic number.

It is an amenable number.

221064665 is a deficient number, since it is larger than the sum of its proper divisors (44212939).

221064665 is an equidigital number, since it uses as much as digits as its factorization.

221064665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44212938.

The product of its (nonzero) digits is 17280, while the sum is 32.

The square root of 221064665 is about 14868.2435075566. The cubic root of 221064665 is about 604.6533223187.

The spelling of 221064665 in words is "two hundred twenty-one million, sixty-four thousand, six hundred sixty-five".