18978621 has 8 divisors (see below), whose sum is σ = 25682784. Its totient is φ = 12463440.

The previous prime is 18978601. The next prime is 18978637. The reversal of 18978621 is 12687981.

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

It is not a de Polignac number, because 18978621 - 2⁷ = 18978493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18978601) 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, 47010 + ... + 47411.

It is an arithmetic number, because the mean of its divisors is an integer number (3210348).

Almost surely, 2^18978621 is an apocalyptic number.

It is an amenable number.

18978621 is a deficient number, since it is larger than the sum of its proper divisors (6704163).

18978621 is an equidigital number, since it uses as much as digits as its factorization.

18978621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94491.

The product of its digits is 48384, while the sum is 42.

The square root of 18978621 is about 4356.4459138155. The cubic root of 18978621 is about 266.7400435228.

The spelling of 18978621 in words is "eighteen million, nine hundred seventy-eight thousand, six hundred twenty-one".