21155155 has 8 divisors (see below), whose sum is σ = 29012832. Its totient is φ = 14506368.

The previous prime is 21155149. The next prime is 21155159. The reversal of 21155155 is 55155112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21155155 - 2⁷ = 21155027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21155159) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 302182 + ... + 302251.

It is an arithmetic number, because the mean of its divisors is an integer number (3626604).

Almost surely, 2^21155155 is an apocalyptic number.

21155155 is a deficient number, since it is larger than the sum of its proper divisors (7857677).

21155155 is an equidigital number, since it uses as much as digits as its factorization.

21155155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604445.

The product of its digits is 1250, while the sum is 25.

The square root of 21155155 is about 4599.4733394162. The cubic root of 21155155 is about 276.5702128250.

The spelling of 21155155 in words is "twenty-one million, one hundred fifty-five thousand, one hundred fifty-five".