20665554 has 48 divisors (see below), whose sum is σ = 51787008. Its totient is φ = 5449248.

The previous prime is 20665549. The next prime is 20665577. The reversal of 20665554 is 45556602.

It is a happy number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 1119 + ... + 6525.

It is an arithmetic number, because the mean of its divisors is an integer number (1078896).

Almost surely, 2^20665554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20665554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25893504).

20665554 is an abundant number, since it is smaller than the sum of its proper divisors (31121454).

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

20665554 is a wasteful number, since it uses less digits than its factorization.

20665554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5439 (or 5432 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 33.

The square root of 20665554 is about 4545.9381869973. The cubic root of 20665554 is about 274.4199520408.

The spelling of 20665554 in words is "twenty million, six hundred sixty-five thousand, five hundred fifty-four".