20509477 has 4 divisors (see below), whose sum is σ = 20527756. Its totient is φ = 20491200.

The previous prime is 20509459. The next prime is 20509487. The reversal of 20509477 is 77490502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2819041 + 17690436 = 1679^2 + 4206^2 .

It is a cyclic number.

It is not a de Polignac number, because 20509477 - 2¹¹ = 20507429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20509457) 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, 7338 + ... + 9739.

It is an arithmetic number, because the mean of its divisors is an integer number (5131939).

Almost surely, 2^20509477 is an apocalyptic number.

It is an amenable number.

20509477 is a deficient number, since it is larger than the sum of its proper divisors (18279).

20509477 is a wasteful number, since it uses less digits than its factorization.

20509477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18278.

The product of its (nonzero) digits is 17640, while the sum is 34.

The square root of 20509477 is about 4528.7390077151. The cubic root of 20509477 is about 273.7273514619.

Adding to 20509477 its reverse (77490502), we get a palindrome (97999979).

The spelling of 20509477 in words is "twenty million, five hundred nine thousand, four hundred seventy-seven".