20209555 has 16 divisors (see below), whose sum is σ = 24714144. Its totient is φ = 15863040.

The previous prime is 20209547. The next prime is 20209561. The reversal of 20209555 is 55590202.

It is not a de Polignac number, because 20209555 - 2³ = 20209547 is a prime.

It is a super-2 number, since 2×20209555² = 816852226596050, which contains 22 as substring.

It is a Duffinian 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, 111565 + ... + 111745.

It is an arithmetic number, because the mean of its divisors is an integer number (1544634).

Almost surely, 2^20209555 is an apocalyptic number.

20209555 is a deficient number, since it is larger than the sum of its proper divisors (4504589).

20209555 is a wasteful number, since it uses less digits than its factorization.

20209555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 486.

The product of its (nonzero) digits is 4500, while the sum is 28.

The square root of 20209555 is about 4495.5038649744. The cubic root of 20209555 is about 272.3865026882.

Adding to 20209555 its reverse (55590202), we get a palindrome (75799757).

The spelling of 20209555 in words is "twenty million, two hundred nine thousand, five hundred fifty-five".