18221861 has 8 divisors (see below), whose sum is σ = 20863680. Its totient is φ = 15589728.

The previous prime is 18221851. The next prime is 18221869. The reversal of 18221861 is 16812281.

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

It is not a de Polignac number, because 18221861 - 2¹⁸ = 17959717 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 (18221869) 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, 2210 + ... + 6428.

It is an arithmetic number, because the mean of its divisors is an integer number (2607960).

Almost surely, 2^18221861 is an apocalyptic number.

It is an amenable number.

18221861 is a deficient number, since it is larger than the sum of its proper divisors (2641819).

18221861 is an equidigital number, since it uses as much as digits as its factorization.

18221861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4843.

The product of its digits is 1536, while the sum is 29.

The square root of 18221861 is about 4268.7071813372. The cubic root of 18221861 is about 263.1464869434.

The spelling of 18221861 in words is "eighteen million, two hundred twenty-one thousand, eight hundred sixty-one".