20091918 has 64 divisors (see below), whose sum is σ = 50600448. Its totient is φ = 5166720.

The previous prime is 20091913. The next prime is 20091923. The reversal of 20091918 is 81919002.

It is an interprime number because it is at equal distance from previous prime (20091913) and next prime (20091923).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20091913) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 72396 + ... + 72672.

It is an arithmetic number, because the mean of its divisors is an integer number (790632).

Almost surely, 2^20091918 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20091918, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25300224).

20091918 is an abundant number, since it is smaller than the sum of its proper divisors (30508530).

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

20091918 is a wasteful number, since it uses less digits than its factorization.

20091918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 457.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 20091918 is about 4482.4009191504. The cubic root of 20091918 is about 271.8569659593.

The spelling of 20091918 in words is "twenty million, ninety-one thousand, nine hundred eighteen".