20840240 has 40 divisors (see below), whose sum is σ = 49014720. Its totient is φ = 8239616.

The previous prime is 20840233. The next prime is 20840263. The reversal of 20840240 is 4204802.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5657 + ... + 8583.

It is an arithmetic number, because the mean of its divisors is an integer number (1225368).

Almost surely, 2^20840240 is an apocalyptic number.

20840240 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 20840240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24507360).

20840240 is an abundant number, since it is smaller than the sum of its proper divisors (28174480).

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

20840240 is a wasteful number, since it uses less digits than its factorization.

20840240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3029 (or 3023 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

The square root of 20840240 is about 4565.1111706069. Note that the first 4 decimals coincide. The cubic root of 20840240 is about 275.1910077961.

The spelling of 20840240 in words is "twenty million, eight hundred forty thousand, two hundred forty".