221306691 has 8 divisors (see below), whose sum is σ = 301353984. Its totient is φ = 144398600.

The previous prime is 221306689. The next prime is 221306693. The reversal of 221306691 is 196603122.

It is an interprime number because it is at equal distance from previous prime (221306689) and next prime (221306693).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221306691 - 2¹ = 221306689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221306693) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 784635 + ... + 784916.

It is an arithmetic number, because the mean of its divisors is an integer number (37669248).

Almost surely, 2^221306691 is an apocalyptic number.

221306691 is a deficient number, since it is larger than the sum of its proper divisors (80047293).

221306691 is a wasteful number, since it uses less digits than its factorization.

221306691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1569601.

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 221306691 is about 14876.3803057061. The cubic root of 221306691 is about 604.8739040076.

The spelling of 221306691 in words is "two hundred twenty-one million, three hundred six thousand, six hundred ninety-one".