20403649 has 6 divisors (see below), whose sum is σ = 23734914. Its totient is φ = 17488800.

The previous prime is 20403589. The next prime is 20403709. The reversal of 20403649 is 94630402.

It is an interprime number because it is at equal distance from previous prime (20403589) and next prime (20403709).

It can be written as a sum of positive squares in only one way, i.e., 17581249 + 2822400 = 4193^2 + 1680^2 .

It is not a de Polignac number, because 20403649 - 2⁷ = 20403521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20403749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 208152 + ... + 208249.

It is an arithmetic number, because the mean of its divisors is an integer number (3955819).

Almost surely, 2^20403649 is an apocalyptic number.

It is an amenable number.

20403649 is a deficient number, since it is larger than the sum of its proper divisors (3331265).

20403649 is an equidigital number, since it uses as much as digits as its factorization.

20403649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416415 (or 416408 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 20403649 is about 4517.0398492818. The cubic root of 20403649 is about 273.2557323166.

The spelling of 20403649 in words is "twenty million, four hundred three thousand, six hundred forty-nine".