20404390 has 16 divisors (see below), whose sum is σ = 37721232. Its totient is φ = 7941024.

The previous prime is 20404387. The next prime is 20404393. The reversal of 20404390 is 9340402.

It is an interprime number because it is at equal distance from previous prime (20404387) and next prime (20404393).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20404393) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 27204 + ... + 27943.

It is an arithmetic number, because the mean of its divisors is an integer number (2357577).

Almost surely, 2^20404390 is an apocalyptic number.

20404390 is a deficient number, since it is larger than the sum of its proper divisors (17316842).

20404390 is a wasteful number, since it uses less digits than its factorization.

20404390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55191.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 20404390 is about 4517.1218712804. The cubic root of 20404390 is about 273.2590402224.

Adding to 20404390 its reverse (9340402), we get a palindrome (29744792).

The spelling of 20404390 in words is "twenty million, four hundred four thousand, three hundred ninety".