20720181 has 8 divisors (see below), whose sum is σ = 28579680. Its totient is φ = 13337072.

The previous prime is 20720153. The next prime is 20720209. The reversal of 20720181 is 18102702.

It is an interprime number because it is at equal distance from previous prime (20720153) and next prime (20720209).

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

It is a cyclic number.

It is not a de Polignac number, because 20720181 - 2¹⁰ = 20719157 is a prime.

It is a super-2 number, since 2×20720181² = 858651801345522, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20720131) 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, 118995 + ... + 119168.

It is an arithmetic number, because the mean of its divisors is an integer number (3572460).

Almost surely, 2^20720181 is an apocalyptic number.

It is an amenable number.

20720181 is a deficient number, since it is larger than the sum of its proper divisors (7859499).

20720181 is a wasteful number, since it uses less digits than its factorization.

20720181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238195.

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 20720181 is about 4551.9425523616. The cubic root of 20720181 is about 274.6615384237.

Adding to 20720181 its reverse (18102702), we get a palindrome (38822883).

The spelling of 20720181 in words is "twenty million, seven hundred twenty thousand, one hundred eighty-one".