20862181 has 4 divisors (see below), whose sum is σ = 21347392. Its totient is φ = 20376972.

The previous prime is 20862169. The next prime is 20862187. The reversal of 20862181 is 18126802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18126802 = 2 ⋅9063401.

It is a cyclic number.

It is not a de Polignac number, because 20862181 - 2²¹ = 18765029 is a prime.

It is a super-2 number, since 2×20862181² = 870461192153522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20862187) 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, 242541 + ... + 242626.

It is an arithmetic number, because the mean of its divisors is an integer number (5336848).

Almost surely, 2^20862181 is an apocalyptic number.

It is an amenable number.

20862181 is a deficient number, since it is larger than the sum of its proper divisors (485211).

20862181 is an equidigital number, since it uses as much as digits as its factorization.

20862181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 485210.

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 20862181 is about 4567.5136562467. The cubic root of 20862181 is about 275.2875493615.

Adding to 20862181 its reverse (18126802), we get a palindrome (38988983).

The spelling of 20862181 in words is "twenty million, eight hundred sixty-two thousand, one hundred eighty-one".