217285231 has 4 divisors (see below), whose sum is σ = 224294464. Its totient is φ = 210276000.

The previous prime is 217285219. The next prime is 217285241. The reversal of 217285231 is 132582712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 217285231 - 2²¹ = 215188079 is a prime.

It is a super-2 number, since 2×217285231² = 94425743221446722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 7009201 = 217285231 / (2 + 1 + 7 + 2 + 8 + 5 + 2 + 3 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 217285193 and 217285202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217285241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3504570 + ... + 3504631.

It is an arithmetic number, because the mean of its divisors is an integer number (56073616).

Almost surely, 2^217285231 is an apocalyptic number.

217285231 is a deficient number, since it is larger than the sum of its proper divisors (7009233).

217285231 is an equidigital number, since it uses as much as digits as its factorization.

217285231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7009232.

The product of its digits is 6720, while the sum is 31.

The square root of 217285231 is about 14740.5980543532. The cubic root of 217285231 is about 601.1876761946.

The spelling of 217285231 in words is "two hundred seventeen million, two hundred eighty-five thousand, two hundred thirty-one".