20405242 has 16 divisors (see below), whose sum is σ = 35959392. Its totient is φ = 8561520.

The previous prime is 20405239. The next prime is 20405251. The reversal of 20405242 is 24250402.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 35388 + ... + 35959.

It is an arithmetic number, because the mean of its divisors is an integer number (2247462).

Almost surely, 2^20405242 is an apocalyptic number.

20405242 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

20405242 is a deficient number, since it is larger than the sum of its proper divisors (15554150).

20405242 is a wasteful number, since it uses less digits than its factorization.

20405242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71373.

The product of its (nonzero) digits is 640, while the sum is 19.

The square root of 20405242 is about 4517.2161781345. The cubic root of 20405242 is about 273.2628435455.

Adding to 20405242 its reverse (24250402), we get a palindrome (44655644).

The spelling of 20405242 in words is "twenty million, four hundred five thousand, two hundred forty-two".