221709691 has 8 divisors (see below), whose sum is σ = 253636064. Its totient is φ = 189846720.

The previous prime is 221709679. The next prime is 221709731. The reversal of 221709691 is 196907122.

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

It is not a de Polignac number, because 221709691 - 2⁵ = 221709659 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221709691.

It is not an unprimeable number, because it can be changed into a prime (221709601) 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, 8100 + ... + 22561.

It is an arithmetic number, because the mean of its divisors is an integer number (31704508).

Almost surely, 2^221709691 is an apocalyptic number.

221709691 is a deficient number, since it is larger than the sum of its proper divisors (31926373).

221709691 is a wasteful number, since it uses less digits than its factorization.

221709691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31701.

The product of its (nonzero) digits is 13608, while the sum is 37.

The square root of 221709691 is about 14889.9191065633. The cubic root of 221709691 is about 605.2408402966.

The spelling of 221709691 in words is "two hundred twenty-one million, seven hundred nine thousand, six hundred ninety-one".