216501331 has 2 divisors, whose sum is σ = 216501332. Its totient is φ = 216501330.

The previous prime is 216501301. The next prime is 216501349. The reversal of 216501331 is 133105612.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 216501331 - 2⁷ = 216501203 is a prime.

It is a super-2 number, since 2×216501331² = 93745652649543122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (216501301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108250665 + 108250666.

It is an arithmetic number, because the mean of its divisors is an integer number (108250666).

Almost surely, 2^216501331 is an apocalyptic number.

216501331 is a deficient number, since it is larger than the sum of its proper divisors (1).

216501331 is an equidigital number, since it uses as much as digits as its factorization.

216501331 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 22.

The square root of 216501331 is about 14713.9841987138. The cubic root of 216501331 is about 600.4638367038.

Adding to 216501331 its reverse (133105612), we get a palindrome (349606943).

The spelling of 216501331 in words is "two hundred sixteen million, five hundred one thousand, three hundred thirty-one".