20945040 has 80 divisors (see below), whose sum is σ = 65406528. Its totient is φ = 5544448.

The previous prime is 20945039. The next prime is 20945051. The reversal of 20945040 is 4054902.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20945040.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47059 + ... + 47501.

Almost surely, 2^20945040 is an apocalyptic number.

20945040 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 20945040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32703264).

20945040 is an abundant number, since it is smaller than the sum of its proper divisors (44461488).

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

20945040 is a wasteful number, since it uses less digits than its factorization.

20945040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 656 (or 650 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 20945040 is about 4576.5751386818. The cubic root of 20945040 is about 275.6515240747.

Adding to 20945040 its reverse (4054902), we get a palindrome (24999942).

The spelling of 20945040 in words is "twenty million, nine hundred forty-five thousand, forty".