216091231 has 2 divisors, whose sum is σ = 216091232. Its totient is φ = 216091230.

The previous prime is 216091201. The next prime is 216091241. The reversal of 216091231 is 132190612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 216091231 - 2⁷ = 216091103 is a prime.

It is a super-2 number, since 2×216091231² = 93390840230190722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 216091196 and 216091205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216091201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108045615 + 108045616.

It is an arithmetic number, because the mean of its divisors is an integer number (108045616).

Almost surely, 2^216091231 is an apocalyptic number.

216091231 is a deficient number, since it is larger than the sum of its proper divisors (1).

216091231 is an equidigital number, since it uses as much as digits as its factorization.

216091231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 216091231 is about 14700.0418706887. The cubic root of 216091231 is about 600.0844612581.

The spelling of 216091231 in words is "two hundred sixteen million, ninety-one thousand, two hundred thirty-one".