20722187 has 4 divisors (see below), whose sum is σ = 20742240. Its totient is φ = 20702136.

The previous prime is 20722181. The next prime is 20722189. The reversal of 20722187 is 78122702.

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

It is a cyclic number.

It is not a de Polignac number, because 20722187 - 2⁴ = 20722171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20722181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8387 + ... + 10572.

It is an arithmetic number, because the mean of its divisors is an integer number (5185560).

Almost surely, 2^20722187 is an apocalyptic number.

20722187 is a deficient number, since it is larger than the sum of its proper divisors (20053).

20722187 is a wasteful number, since it uses less digits than its factorization.

20722187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20052.

The product of its (nonzero) digits is 3136, while the sum is 29.

The square root of 20722187 is about 4552.1628925160. The cubic root of 20722187 is about 274.6704018158.

Adding to 20722187 its reverse (78122702), we get a palindrome (98844889).

The spelling of 20722187 in words is "twenty million, seven hundred twenty-two thousand, one hundred eighty-seven".