21531055 has 32 divisors (see below), whose sum is σ = 32256000. Its totient is φ = 13433472.

The previous prime is 21531049. The next prime is 21531071. The reversal of 21531055 is 55013512.

It is not a de Polignac number, because 21531055 - 2⁵ = 21531023 is a prime.

It is a plaindrome in base 16.

It is a zygodrome in base 3.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 35646 + ... + 36244.

It is an arithmetic number, because the mean of its divisors is an integer number (1008000).

Almost surely, 2^21531055 is an apocalyptic number.

21531055 is a deficient number, since it is larger than the sum of its proper divisors (10724945).

21531055 is a wasteful number, since it uses less digits than its factorization.

21531055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 703.

The product of its (nonzero) digits is 750, while the sum is 22.

The square root of 21531055 is about 4640.1567861442. The cubic root of 21531055 is about 278.1987046171.

Adding to 21531055 its reverse (55013512), we get a palindrome (76544567).

The spelling of 21531055 in words is "twenty-one million, five hundred thirty-one thousand, fifty-five".