20215404 has 72 divisors (see below), whose sum is σ = 56609280. Its totient is φ = 6031200.

The previous prime is 20215381. The next prime is 20215417. The reversal of 20215404 is 40451202.

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

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, 27757 + ... + 28475.

It is an arithmetic number, because the mean of its divisors is an integer number (786240).

Almost surely, 2^20215404 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20215404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28304640).

20215404 is an abundant number, since it is smaller than the sum of its proper divisors (36393876).

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

20215404 is a wasteful number, since it uses less digits than its factorization.

20215404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811 (or 806 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 20215404 is about 4496.1543567809. The cubic root of 20215404 is about 272.4127779654.

Adding to 20215404 its reverse (40451202), we get a palindrome (60666606).

The spelling of 20215404 in words is "twenty million, two hundred fifteen thousand, four hundred four".