20509399 has 8 divisors (see below), whose sum is σ = 21456000. Its totient is φ = 19567416.

The previous prime is 20509373. The next prime is 20509421. The reversal of 20509399 is 99390502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20509399 - 2⁷ = 20509271 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 (20509309) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10584 + ... + 12370.

It is an arithmetic number, because the mean of its divisors is an integer number (2682000).

Almost surely, 2^20509399 is an apocalyptic number.

20509399 is a deficient number, since it is larger than the sum of its proper divisors (946601).

20509399 is a wasteful number, since it uses less digits than its factorization.

20509399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2309.

The product of its (nonzero) digits is 21870, while the sum is 37.

The square root of 20509399 is about 4528.7303960382. The cubic root of 20509399 is about 273.7270044555.

It can be divided in two parts, 2050 and 9399, that added together give a square (11449 = 107²).

The spelling of 20509399 in words is "twenty million, five hundred nine thousand, three hundred ninety-nine".