18721983 has 8 divisors (see below), whose sum is σ = 28528768. Its totient is φ = 10698264.

The previous prime is 18721979. The next prime is 18721987. The reversal of 18721983 is 38912781.

It is an interprime number because it is at equal distance from previous prime (18721979) and next prime (18721987).

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

It is not a de Polignac number, because 18721983 - 2² = 18721979 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 (18721987) 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, 445741 + ... + 445782.

It is an arithmetic number, because the mean of its divisors is an integer number (3566096).

Almost surely, 2^18721983 is an apocalyptic number.

18721983 is a deficient number, since it is larger than the sum of its proper divisors (9806785).

18721983 is an equidigital number, since it uses as much as digits as its factorization.

18721983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 891533.

The product of its digits is 24192, while the sum is 39.

The square root of 18721983 is about 4326.8906850070. The cubic root of 18721983 is about 265.5322540888.

The spelling of 18721983 in words is "eighteen million, seven hundred twenty-one thousand, nine hundred eighty-three".