20513440 has 48 divisors (see below), whose sum is σ = 50145480. Its totient is φ = 7920640.

The previous prime is 20513431. The next prime is 20513443. The reversal of 20513440 is 4431502.

It can be written as a sum of positive squares in 4 ways, for example, as 19044496 + 1468944 = 4364^2 + 1212^2 .

It is not an unprimeable number, because it can be changed into a prime (20513443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2430 + ... + 6850.

Almost surely, 2^20513440 is an apocalyptic number.

20513440 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 20513440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25072740).

20513440 is an abundant number, since it is smaller than the sum of its proper divisors (29632040).

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

20513440 is a wasteful number, since it uses less digits than its factorization.

20513440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4465 (or 4457 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20513440 is about 4529.1765255949. The cubic root of 20513440 is about 273.7449808995.

Adding to 20513440 its reverse (4431502), we get a palindrome (24944942).

The spelling of 20513440 in words is "twenty million, five hundred thirteen thousand, four hundred forty".