216716645 has 4 divisors (see below), whose sum is σ = 260059980. Its totient is φ = 173373312.

The previous prime is 216716639. The next prime is 216716651. The reversal of 216716645 is 546617612.

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

It is an interprime number because it is at equal distance from previous prime (216716639) and next prime (216716651).

It can be written as a sum of positive squares in 2 ways, for example, as 117375556 + 99341089 = 10834^2 + 9967^2 .

It is a cyclic number.

It is not a de Polignac number, because 216716645 - 2¹⁰ = 216715621 is a prime.

It is a super-2 number, since 2×216716645² = 93932208440112050, which contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 216716599 and 216716608.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21671660 + ... + 21671669.

It is an arithmetic number, because the mean of its divisors is an integer number (65014995).

Almost surely, 2^216716645 is an apocalyptic number.

It is an amenable number.

216716645 is a deficient number, since it is larger than the sum of its proper divisors (43343335).

216716645 is an equidigital number, since it uses as much as digits as its factorization.

216716645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43343334.

The product of its digits is 60480, while the sum is 38.

The square root of 216716645 is about 14721.2990255616. The cubic root of 216716645 is about 600.6628276813.

The spelling of 216716645 in words is "two hundred sixteen million, seven hundred sixteen thousand, six hundred forty-five".