21055049 has 4 divisors (see below), whose sum is σ = 21130260. Its totient is φ = 20979840.

The previous prime is 21055043. The next prime is 21055063. The reversal of 21055049 is 94055012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18215824 + 2839225 = 4268^2 + 1685^2 .

It is a cyclic number.

It is not a de Polignac number, because 21055049 - 2⁴ = 21055033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21055043) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 37184 + ... + 37745.

It is an arithmetic number, because the mean of its divisors is an integer number (5282565).

Almost surely, 2^21055049 is an apocalyptic number.

It is an amenable number.

21055049 is a deficient number, since it is larger than the sum of its proper divisors (75211).

21055049 is an equidigital number, since it uses as much as digits as its factorization.

21055049 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75210.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21055049 is about 4588.5781022012. The cubic root of 21055049 is about 276.1332803391.

The spelling of 21055049 in words is "twenty-one million, fifty-five thousand, forty-nine".