20696509 has 4 divisors (see below), whose sum is σ = 20816316. Its totient is φ = 20576704.

The previous prime is 20696503. The next prime is 20696521. The reversal of 20696509 is 90569602.

It is a happy number.

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 16990884 + 3705625 = 4122^2 + 1925^2 .

It is a cyclic number.

It is not a de Polignac number, because 20696509 - 2⁷ = 20696381 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 (20696503) 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 in 3 ways as a sum of consecutive naturals, for example, 59644 + ... + 59989.

It is an arithmetic number, because the mean of its divisors is an integer number (5204079).

Almost surely, 2^20696509 is an apocalyptic number.

It is an amenable number.

20696509 is a deficient number, since it is larger than the sum of its proper divisors (119807).

20696509 is a wasteful number, since it uses less digits than its factorization.

20696509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 119806.

The product of its (nonzero) digits is 29160, while the sum is 37.

The square root of 20696509 is about 4549.3416007154. The cubic root of 20696509 is about 274.5569018615.

The spelling of 20696509 in words is "twenty million, six hundred ninety-six thousand, five hundred nine".