18721101 has 8 divisors (see below), whose sum is σ = 28527424. Its totient is φ = 10697760.

The previous prime is 18721091. The next prime is 18721123. The reversal of 18721101 is 10112781.

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

It is not a de Polignac number, because 18721101 - 2⁹ = 18720589 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 891481 = 18721101 / (1 + 8 + 7 + 2 + 1 + 1 + 0 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18721141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 445720 + ... + 445761.

It is an arithmetic number, because the mean of its divisors is an integer number (3565928).

Almost surely, 2^18721101 is an apocalyptic number.

It is an amenable number.

18721101 is a deficient number, since it is larger than the sum of its proper divisors (9806323).

18721101 is an equidigital number, since it uses as much as digits as its factorization.

18721101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 891491.

The product of its (nonzero) digits is 112, while the sum is 21.

The square root of 18721101 is about 4326.7887630436. The cubic root of 18721101 is about 265.5280842469.

Adding to 18721101 its reverse (10112781), we get a palindrome (28833882).

The spelling of 18721101 in words is "eighteen million, seven hundred twenty-one thousand, one hundred one".