20538840 has 128 divisors (see below), whose sum is σ = 72000000. Its totient is φ = 4685184.

The previous prime is 20538823. The next prime is 20538841. The reversal of 20538840 is 4883502.

It is a super-3 number, since 3×20538840³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20538798 and 20538807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20538841) 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 31 ways as a sum of consecutive naturals, for example, 40911 + ... + 41409.

It is an arithmetic number, because the mean of its divisors is an integer number (562500).

Almost surely, 2^20538840 is an apocalyptic number.

20538840 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 20538840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36000000).

20538840 is an abundant number, since it is smaller than the sum of its proper divisors (51461160).

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

20538840 is a wasteful number, since it uses less digits than its factorization.

20538840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 534 (or 516 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 30.

The square root of 20538840 is about 4531.9796998663. The cubic root of 20538840 is about 273.8579191272.

The spelling of 20538840 in words is "twenty million, five hundred thirty-eight thousand, eight hundred forty".