20353640 has 16 divisors (see below), whose sum is σ = 45795780. Its totient is φ = 8141440.

The previous prime is 20353633. The next prime is 20353649. The reversal of 20353640 is 4635302.

It can be written as a sum of positive squares in 2 ways, for example, as 19838116 + 515524 = 4454^2 + 718^2 .

It is a super-2 number, since 2×20353640² = 828541322499200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20353649) 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 3 ways as a sum of consecutive naturals, for example, 254381 + ... + 254460.

Almost surely, 2^20353640 is an apocalyptic number.

20353640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20353640 is an abundant number, since it is smaller than the sum of its proper divisors (25442140).

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

20353640 is a wasteful number, since it uses less digits than its factorization.

20353640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 508852 (or 508848 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 23.

The square root of 20353640 is about 4511.5008589160. The cubic root of 20353640 is about 273.0323012762.

Adding to 20353640 its reverse (4635302), we get a palindrome (24988942).

The spelling of 20353640 in words is "twenty million, three hundred fifty-three thousand, six hundred forty".