20816555 has 16 divisors (see below), whose sum is σ = 25632288. Its totient is φ = 16224000.

The previous prime is 20816539. The next prime is 20816569. The reversal of 20816555 is 55561802.

It is not a de Polignac number, because 20816555 - 2⁴ = 20816539 is a prime.

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, 39695 + ... + 40215.

It is an arithmetic number, because the mean of its divisors is an integer number (1602018).

Almost surely, 2^20816555 is an apocalyptic number.

20816555 is a deficient number, since it is larger than the sum of its proper divisors (4815733).

20816555 is a wasteful number, since it uses less digits than its factorization.

20816555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 718.

The product of its (nonzero) digits is 12000, while the sum is 32.

The square root of 20816555 is about 4562.5163013407. The cubic root of 20816555 is about 275.0867164543.

The spelling of 20816555 in words is "twenty million, eight hundred sixteen thousand, five hundred fifty-five".