18477221 has 8 divisors (see below), whose sum is σ = 21225600. Its totient is φ = 15756048.

The previous prime is 18477197. The next prime is 18477223. The reversal of 18477221 is 12277481.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-18477221 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 (18477223) 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, 5321 + ... + 8078.

It is an arithmetic number, because the mean of its divisors is an integer number (2653200).

Almost surely, 2^18477221 is an apocalyptic number.

It is an amenable number.

18477221 is a deficient number, since it is larger than the sum of its proper divisors (2748379).

18477221 is a wasteful number, since it uses less digits than its factorization.

18477221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13603.

The product of its digits is 6272, while the sum is 32.

The square root of 18477221 is about 4298.5138129358. The cubic root of 18477221 is about 264.3700284467.

The spelling of 18477221 in words is "eighteen million, four hundred seventy-seven thousand, two hundred twenty-one".