216165621 has 8 divisors (see below), whose sum is σ = 329395264. Its totient is φ = 123523200.

The previous prime is 216165613. The next prime is 216165637. The reversal of 216165621 is 126561612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 216165621 - 2³ = 216165613 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216165721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5146780 + ... + 5146821.

It is an arithmetic number, because the mean of its divisors is an integer number (41174408).

Almost surely, 2^216165621 is an apocalyptic number.

216165621 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

216165621 is a deficient number, since it is larger than the sum of its proper divisors (113229643).

216165621 is a wasteful number, since it uses less digits than its factorization.

216165621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10293611.

The product of its digits is 4320, while the sum is 30.

The square root of 216165621 is about 14702.5719178653. The cubic root of 216165621 is about 600.1533135993.

The spelling of 216165621 in words is "two hundred sixteen million, one hundred sixty-five thousand, six hundred twenty-one".