21532218 has 16 divisors (see below), whose sum is σ = 43158720. Its totient is φ = 7161696.

The previous prime is 21532201. The next prime is 21532219. The reversal of 21532218 is 81223512.

It is not an unprimeable number, because it can be changed into a prime (21532219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 763 + ... + 6606.

It is an arithmetic number, because the mean of its divisors is an integer number (2697420).

Almost surely, 2^21532218 is an apocalyptic number.

21532218 is an abundant number, since it is smaller than the sum of its proper divisors (21626502).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21532218 is a wasteful number, since it uses less digits than its factorization.

21532218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7861.

The product of its digits is 960, while the sum is 24.

The square root of 21532218 is about 4640.2821034933. The cubic root of 21532218 is about 278.2037134949.

It can be divided in two parts, 2153 and 2218, that added together give a triangular number (4371 = T₉₃).

The spelling of 21532218 in words is "twenty-one million, five hundred thirty-two thousand, two hundred eighteen".