165721207 has 4 divisors (see below), whose sum is σ = 165783376. Its totient is φ = 165659040.

The previous prime is 165721189. The next prime is 165721229. The reversal of 165721207 is 702127561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 702127561 = 7207 ⋅97423.

It is a cyclic number.

It is not a de Polignac number, because 165721207 - 2²³ = 157332599 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 (165721267) 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, 26898 + ... + 32479.

It is an arithmetic number, because the mean of its divisors is an integer number (41445844).

Almost surely, 2^165721207 is an apocalyptic number.

165721207 is a deficient number, since it is larger than the sum of its proper divisors (62169).

165721207 is an equidigital number, since it uses as much as digits as its factorization.

165721207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62168.

The product of its (nonzero) digits is 5880, while the sum is 31.

The square root of 165721207 is about 12873.2749135564. The cubic root of 165721207 is about 549.2786211969.

Adding to 165721207 its reverse (702127561), we get a palindrome (867848768).

The spelling of 165721207 in words is "one hundred sixty-five million, seven hundred twenty-one thousand, two hundred seven".