20403709 has 2 divisors, whose sum is σ = 20403710. Its totient is φ = 20403708.

The previous prime is 20403589. The next prime is 20403727. The reversal of 20403709 is 90730402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17614809 + 2788900 = 4197^2 + 1670^2 .

It is a cyclic number.

It is not a de Polignac number, because 20403709 - 2⁹ = 20403197 is a prime.

It is a super-2 number, since 2×20403709² = 832622681913362, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20403749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10201854 + 10201855.

It is an arithmetic number, because the mean of its divisors is an integer number (10201855).

Almost surely, 2^20403709 is an apocalyptic number.

It is an amenable number.

20403709 is a deficient number, since it is larger than the sum of its proper divisors (1).

20403709 is an equidigital number, since it uses as much as digits as its factorization.

20403709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1512, while the sum is 25.

The square root of 20403709 is about 4517.0464907946. The cubic root of 20403709 is about 273.2560001662.

It can be divided in two parts, 20403 and 709, that added together give a palindrome (21112).

The spelling of 20403709 in words is "twenty million, four hundred three thousand, seven hundred nine".