20915440 has 160 divisors (see below), whose sum is σ = 63745920. Its totient is φ = 6230016.

The previous prime is 20915417. The next prime is 20915459. The reversal of 20915440 is 4451902.

It is a nialpdrome in base 13.

It is a zygodrome in base 13.

It is a congruent 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 31 ways as a sum of consecutive naturals, for example, 1230312 + ... + 1230328.

It is an arithmetic number, because the mean of its divisors is an integer number (398412).

Almost surely, 2^20915440 is an apocalyptic number.

20915440 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 20915440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31872960).

20915440 is an abundant number, since it is smaller than the sum of its proper divisors (42830480).

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

20915440 is a wasteful number, since it uses less digits than its factorization.

20915440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76 (or 44 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 20915440 is about 4573.3401360494. The cubic root of 20915440 is about 275.5216105525.

The spelling of 20915440 in words is "twenty million, nine hundred fifteen thousand, four hundred forty".