20351440 has 40 divisors (see below), whose sum is σ = 47996928. Its totient is φ = 8023680.

The previous prime is 20351437. The next prime is 20351447. The reversal of 20351440 is 4415302.

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

It is a super-2 number, since 2×20351440² = 828362220147200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20351447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3889 + ... + 7471.

Almost surely, 2^20351440 is an apocalyptic number.

20351440 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 20351440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23998464).

20351440 is an abundant number, since it is smaller than the sum of its proper divisors (27645488).

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

20351440 is a wasteful number, since it uses less digits than its factorization.

20351440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3667 (or 3661 counting only the distinct ones).

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

The square root of 20351440 is about 4511.2570310280. The cubic root of 20351440 is about 273.0224636795.

Adding to 20351440 its reverse (4415302), we get a palindrome (24766742).

The spelling of 20351440 in words is "twenty million, three hundred fifty-one thousand, four hundred forty".