21545155 has 16 divisors (see below), whose sum is σ = 26982144. Its totient is φ = 16496640.

The previous prime is 21545149. The next prime is 21545179. The reversal of 21545155 is 55154512.

It is not a de Polignac number, because 21545155 - 2²³ = 13156547 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14319 + ... + 15751.

It is an arithmetic number, because the mean of its divisors is an integer number (1686384).

Almost surely, 2^21545155 is an apocalyptic number.

21545155 is a deficient number, since it is larger than the sum of its proper divisors (5436989).

21545155 is a wasteful number, since it uses less digits than its factorization.

21545155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1566.

The product of its digits is 5000, while the sum is 28.

The square root of 21545155 is about 4641.6758826958. The cubic root of 21545155 is about 278.2594191801.

Adding to 21545155 its reverse (55154512), we get a palindrome (76699667).

The spelling of 21545155 in words is "twenty-one million, five hundred forty-five thousand, one hundred fifty-five".