20705040 has 120 divisors (see below), whose sum is σ = 70363800. Its totient is φ = 5455872.

The previous prime is 20705029. The next prime is 20705053. The reversal of 20705040 is 4050702.

20705040 = T₁₁₅ + T₁₁₆ + ... + T₅₀₀.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 20736 + 20684304 = 144^2 + 4548^2 .

It is a tau number, because it is divible by the number of its divisors (120).

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 polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 107184 + ... + 107376.

It is an arithmetic number, because the mean of its divisors is an integer number (586365).

Almost surely, 2^20705040 is an apocalyptic number.

20705040 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 20705040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35181900).

20705040 is an abundant number, since it is smaller than the sum of its proper divisors (49658760).

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

20705040 is a wasteful number, since it uses less digits than its factorization.

20705040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361 (or 352 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 18.

The square root of 20705040 is about 4550.2791123183. The cubic root of 20705040 is about 274.5946203512.

Adding to 20705040 its reverse (4050702), we get a palindrome (24755742).

The spelling of 20705040 in words is "twenty million, seven hundred five thousand, forty".