216331645 has 4 divisors (see below), whose sum is σ = 259597980. Its totient is φ = 173065312.

The previous prime is 216331603. The next prime is 216331649. The reversal of 216331645 is 546133612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 131194116 + 85137529 = 11454^2 + 9227^2 .

It is a cyclic number.

It is not a de Polignac number, because 216331645 - 2⁹ = 216331133 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216331649) 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, 21633160 + ... + 21633169.

It is an arithmetic number, because the mean of its divisors is an integer number (64899495).

Almost surely, 2^216331645 is an apocalyptic number.

It is an amenable number.

216331645 is a deficient number, since it is larger than the sum of its proper divisors (43266335).

216331645 is an equidigital number, since it uses as much as digits as its factorization.

216331645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43266334.

The product of its digits is 12960, while the sum is 31.

The square root of 216331645 is about 14708.2169211635. The cubic root of 216331645 is about 600.3069216754.

The spelling of 216331645 in words is "two hundred sixteen million, three hundred thirty-one thousand, six hundred forty-five".