216826509 has 4 divisors (see below), whose sum is σ = 289102016. Its totient is φ = 144551004.

The previous prime is 216826507. The next prime is 216826529. The reversal of 216826509 is 905628612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 216826509 - 2¹ = 216826507 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216826507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36137749 + ... + 36137754.

It is an arithmetic number, because the mean of its divisors is an integer number (72275504).

Almost surely, 2^216826509 is an apocalyptic number.

It is an amenable number.

216826509 is a deficient number, since it is larger than the sum of its proper divisors (72275507).

216826509 is an equidigital number, since it uses as much as digits as its factorization.

216826509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72275506.

The product of its (nonzero) digits is 51840, while the sum is 39.

The square root of 216826509 is about 14725.0300169473. The cubic root of 216826509 is about 600.7643120761.

The spelling of 216826509 in words is "two hundred sixteen million, eight hundred twenty-six thousand, five hundred nine".