20007840 has 96 divisors (see below), whose sum is σ = 63999936. Its totient is φ = 5253120.

The previous prime is 20007811. The next prime is 20007847. The reversal of 20007840 is 4870002.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×20007840² = 800627322931200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20007847) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34755 + ... + 35325.

It is an arithmetic number, because the mean of its divisors is an integer number (666666).

Almost surely, 2^20007840 is an apocalyptic number.

20007840 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 20007840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31999968).

20007840 is an abundant number, since it is smaller than the sum of its proper divisors (43992096).

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

20007840 is a wasteful number, since it uses less digits than its factorization.

20007840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662 (or 654 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 20007840 is about 4473.0124077628. The cubic root of 20007840 is about 271.4772254162.

Adding to 20007840 its reverse (4870002), we get a palindrome (24877842).

The spelling of 20007840 in words is "twenty million, seven thousand, eight hundred forty".