20405502 has 96 divisors (see below), whose sum is σ = 51367680. Its totient is φ = 5806080.

The previous prime is 20405501. The next prime is 20405513. The reversal of 20405502 is 20550402.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20405501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 210318 + ... + 210414.

It is an arithmetic number, because the mean of its divisors is an integer number (535080).

Almost surely, 2^20405502 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20405502, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25683840).

20405502 is an abundant number, since it is smaller than the sum of its proper divisors (30962178).

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

20405502 is a wasteful number, since it uses less digits than its factorization.

20405502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178 (or 175 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 18.

The square root of 20405502 is about 4517.2449568293. The cubic root of 20405502 is about 273.2640041629.

Adding to 20405502 its reverse (20550402), we get a palindrome (40955904).

The spelling of 20405502 in words is "twenty million, four hundred five thousand, five hundred two".