21081255 has 16 divisors (see below), whose sum is σ = 36324960. Its totient is φ = 10378368.

The previous prime is 21081217. The next prime is 21081259. The reversal of 21081255 is 55218012.

It is not a de Polignac number, because 21081255 - 2⁹ = 21080743 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081259) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53860 + ... + 54249.

It is an arithmetic number, because the mean of its divisors is an integer number (2270310).

Almost surely, 2^21081255 is an apocalyptic number.

21081255 is a deficient number, since it is larger than the sum of its proper divisors (15243705).

21081255 is a wasteful number, since it uses less digits than its factorization.

21081255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108130.

The product of its (nonzero) digits is 800, while the sum is 24.

The square root of 21081255 is about 4591.4327829121. The cubic root of 21081255 is about 276.2477952091.

Adding to 21081255 its reverse (55218012), we get a palindrome (76299267).

The spelling of 21081255 in words is "twenty-one million, eighty-one thousand, two hundred fifty-five".