20215440 has 240 divisors, whose sum is σ = 81423360. Its totient is φ = 4596480.

The previous prime is 20215417. The next prime is 20215451. The reversal of 20215440 is 4451202.

It is a tau number, because it is divible by the number of its divisors (240).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 105745 + ... + 105935.

It is an arithmetic number, because the mean of its divisors is an integer number (339264).

Almost surely, 2^20215440 is an apocalyptic number.

20215440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20215440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40711680).

20215440 is an abundant number, since it is smaller than the sum of its proper divisors (61207920).

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

20215440 is a wasteful number, since it uses less digits than its factorization.

20215440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227 (or 208 counting only the distinct ones).

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

The square root of 20215440 is about 4496.1583602004. The cubic root of 20215440 is about 272.4129396714.

Adding to 20215440 its reverse (4451202), we get a palindrome (24666642).

The spelling of 20215440 in words is "twenty million, two hundred fifteen thousand, four hundred forty".