19918305 has 80 divisors (see below), whose sum is σ = 41399424. Its totient is φ = 9054720.

The previous prime is 19918303. The next prime is 19918313. The reversal of 19918305 is 50381991.

It is a happy number.

It is not a de Polignac number, because 19918305 - 2¹ = 19918303 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19918305.

It is not an unprimeable number, because it can be changed into a prime (19918303) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 75604 + ... + 75866.

Almost surely, 2^19918305 is an apocalyptic number.

19918305 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

19918305 is an abundant number, since it is smaller than the sum of its proper divisors (21481119).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19918305 is a wasteful number, since it uses less digits than its factorization.

19918305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308 (or 299 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 19918305 is about 4462.9928299293. The cubic root of 19918305 is about 271.0716667074.

It can be divided in two parts, 1991 and 8305, that added together give a triangular number (10296 = T₁₄₃).

The spelling of 19918305 in words is "nineteen million, nine hundred eighteen thousand, three hundred five".