20509265 has 16 divisors (see below), whose sum is σ = 29608320. Its totient is φ = 13322880.

The previous prime is 20509241. The next prime is 20509271. The reversal of 20509265 is 56290502.

It is not a de Polignac number, because 20509265 - 2¹² = 20505169 is a prime.

It is a super-3 number, since 3×20509265³ (a number of 23 digits) contains 333 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14756 + ... + 16085.

It is an arithmetic number, because the mean of its divisors is an integer number (1850520).

Almost surely, 2^20509265 is an apocalyptic number.

It is an amenable number.

20509265 is a deficient number, since it is larger than the sum of its proper divisors (9099055).

20509265 is a wasteful number, since it uses less digits than its factorization.

20509265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30872.

The product of its (nonzero) digits is 5400, while the sum is 29.

The square root of 20509265 is about 4528.7156015807. The cubic root of 20509265 is about 273.7264083142.

Adding to 20509265 its reverse (56290502), we get a palindrome (76799767).

The spelling of 20509265 in words is "twenty million, five hundred nine thousand, two hundred sixty-five".