221765231 has 2 divisors, whose sum is σ = 221765232. Its totient is φ = 221765230.

The previous prime is 221765189. The next prime is 221765237. The reversal of 221765231 is 132567122.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221765231 is a prime.

It is a super-2 number, since 2×221765231² = 98359635360966722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 221765194 and 221765203.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221765237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110882615 + 110882616.

It is an arithmetic number, because the mean of its divisors is an integer number (110882616).

Almost surely, 2^221765231 is an apocalyptic number.

221765231 is a deficient number, since it is larger than the sum of its proper divisors (1).

221765231 is an equidigital number, since it uses as much as digits as its factorization.

221765231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 29.

The square root of 221765231 is about 14891.7840099835. The cubic root of 221765231 is about 605.2913752545.

The spelling of 221765231 in words is "two hundred twenty-one million, seven hundred sixty-five thousand, two hundred thirty-one".