21055115 has 4 divisors (see below), whose sum is σ = 25266144. Its totient is φ = 16844088.

The previous prime is 21055087. The next prime is 21055123. The reversal of 21055115 is 51155012.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21055115 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2105507 + ... + 2105516.

It is an arithmetic number, because the mean of its divisors is an integer number (6316536).

Almost surely, 2^21055115 is an apocalyptic number.

21055115 is a deficient number, since it is larger than the sum of its proper divisors (4211029).

21055115 is an equidigital number, since it uses as much as digits as its factorization.

21055115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4211028.

The product of its (nonzero) digits is 250, while the sum is 20.

The square root of 21055115 is about 4588.5852939659. The cubic root of 21055115 is about 276.1335688649.

The spelling of 21055115 in words is "twenty-one million, fifty-five thousand, one hundred fifteen".