20505401 has 4 divisors (see below), whose sum is σ = 23434752. Its totient is φ = 17576052.

The previous prime is 20505379. The next prime is 20505409. The reversal of 20505401 is 10450502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20505401 - 2¹⁰ = 20504377 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20505401.

It is not an unprimeable number, because it can be changed into a prime (20505409) 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 3 ways as a sum of consecutive naturals, for example, 1464665 + ... + 1464678.

It is an arithmetic number, because the mean of its divisors is an integer number (5858688).

Almost surely, 2^20505401 is an apocalyptic number.

It is an amenable number.

20505401 is a deficient number, since it is larger than the sum of its proper divisors (2929351).

20505401 is an equidigital number, since it uses as much as digits as its factorization.

20505401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2929350.

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 20505401 is about 4528.2889704611. The cubic root of 20505401 is about 273.7092169738.

Adding to 20505401 its reverse (10450502), we get a palindrome (30955903).

The spelling of 20505401 in words is "twenty million, five hundred five thousand, four hundred one".