21177055 has 4 divisors (see below), whose sum is σ = 25412472. Its totient is φ = 16941640.

The previous prime is 21177041. The next prime is 21177059. The reversal of 21177055 is 55077112.

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

It is not a de Polignac number, because 21177055 - 2¹⁵ = 21144287 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 (21177059) by changing a digit.

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, 2117701 + ... + 2117710.

It is an arithmetic number, because the mean of its divisors is an integer number (6353118).

Almost surely, 2^21177055 is an apocalyptic number.

21177055 is a deficient number, since it is larger than the sum of its proper divisors (4235417).

21177055 is an equidigital number, since it uses as much as digits as its factorization.

21177055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4235416.

The product of its (nonzero) digits is 2450, while the sum is 28.

The square root of 21177055 is about 4601.8534309558. The cubic root of 21177055 is about 276.6656158732.

The spelling of 21177055 in words is "twenty-one million, one hundred seventy-seven thousand, fifty-five".