20671555 has 4 divisors (see below), whose sum is σ = 24805872. Its totient is φ = 16537240.

The previous prime is 20671543. The next prime is 20671603. The reversal of 20671555 is 55517602.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20671555 - 2¹⁷ = 20540483 is a prime.

It is a super-2 number, since 2×20671555² = 854626372236050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2067151 + ... + 2067160.

It is an arithmetic number, because the mean of its divisors is an integer number (6201468).

Almost surely, 2^20671555 is an apocalyptic number.

20671555 is a deficient number, since it is larger than the sum of its proper divisors (4134317).

20671555 is an equidigital number, since it uses as much as digits as its factorization.

20671555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4134316.

The product of its (nonzero) digits is 10500, while the sum is 31.

The square root of 20671555 is about 4546.5981788586. The cubic root of 20671555 is about 274.4465120959.

The spelling of 20671555 in words is "twenty million, six hundred seventy-one thousand, five hundred fifty-five".