221697 has 40 divisors (see below), whose sum is σ = 418176. Its totient is φ = 114048.

The previous prime is 221677. The next prime is 221707. The reversal of 221697 is 796122.

It is not a de Polignac number, because 221697 - 2¹⁰ = 220673 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 221697.

It is not an unprimeable number, because it can be changed into a prime (221657) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 9628 + ... + 9650.

It is a Proth number, since it is equal to 433 ⋅ 2⁹ + 1 and 433 < 2⁹.

2²²¹⁶⁹⁷ is an apocalyptic number.

221697 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

221697 is a deficient number, since it is larger than the sum of its proper divisors (196479).

221697 is a wasteful number, since it uses less digits than its factorization.

221697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59 (or 50 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 221697 is about 470.8471089430. The cubic root of 221697 is about 60.5229291774.

The spelling of 221697 in words is "two hundred twenty-one thousand, six hundred ninety-seven".