20405394 has 12 divisors (see below), whose sum is σ = 44211726. Its totient is φ = 6801792.

The previous prime is 20405387. The next prime is 20405443. The reversal of 20405394 is 49350402.

It can be written as a sum of positive squares in only one way, i.e., 12638025 + 7767369 = 3555^2 + 2787^2 .

It is a Curzon 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 5 ways as a sum of consecutive naturals, for example, 566799 + ... + 566834.

Almost surely, 2^20405394 is an apocalyptic number.

20405394 is an abundant number, since it is smaller than the sum of its proper divisors (23806332).

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

20405394 is a wasteful number, since it uses less digits than its factorization.

20405394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1133641 (or 1133638 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 20405394 is about 4517.2330026245. The cubic root of 20405394 is about 273.2635220615.

Adding to 20405394 its reverse (49350402), we get a palindrome (69755796).

The spelling of 20405394 in words is "twenty million, four hundred five thousand, three hundred ninety-four".