21445155 has 20 divisors (see below), whose sum is σ = 38443152. Its totient is φ = 11437200.

The previous prime is 21445147. The next prime is 21445157. The reversal of 21445155 is 55154412.

21445155 is a `hidden beast` number, since 2 + 144 + 515 + 5 = 666.

It is not a de Polignac number, because 21445155 - 2³ = 21445147 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21445157) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 26071 + ... + 26880.

Almost surely, 2^21445155 is an apocalyptic number.

21445155 is a deficient number, since it is larger than the sum of its proper divisors (16997997).

21445155 is an equidigital number, since it uses as much as digits as its factorization.

21445155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52968 (or 52959 counting only the distinct ones).

The product of its digits is 4000, while the sum is 27.

The square root of 21445155 is about 4630.8913828765. The cubic root of 21445155 is about 277.8282456154.

Adding to 21445155 its reverse (55154412), we get a palindrome (76599567).

It can be divided in two parts, 214 and 45155, that added together give a square (45369 = 213²).

The spelling of 21445155 in words is "twenty-one million, four hundred forty-five thousand, one hundred fifty-five".