20722165 has 8 divisors (see below), whose sum is σ = 24947928. Its totient is φ = 16523520.

The previous prime is 20722129. The next prime is 20722171. The reversal of 20722165 is 56122702.

It can be written as a sum of positive squares in 4 ways, for example, as 2137444 + 18584721 = 1462^2 + 4311^2 .

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

It is not a de Polignac number, because 20722165 - 2¹⁷ = 20591093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5056 + ... + 8185.

It is an arithmetic number, because the mean of its divisors is an integer number (3118491).

Almost surely, 2^20722165 is an apocalyptic number.

It is an amenable number.

20722165 is a deficient number, since it is larger than the sum of its proper divisors (4225763).

20722165 is a wasteful number, since it uses less digits than its factorization.

20722165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13559.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 20722165 is about 4552.1604760817. The cubic root of 20722165 is about 274.6703046132.

Adding to 20722165 its reverse (56122702), we get a palindrome (76844867).

The spelling of 20722165 in words is "twenty million, seven hundred twenty-two thousand, one hundred sixty-five".