21271684 has 18 divisors (see below), whose sum is σ = 43303470. Its totient is φ = 9116352.

The previous prime is 21271667. The next prime is 21271699. The reversal of 21271684 is 48617212.

It can be written as a sum of positive squares in only one way, i.e., 20958084 + 313600 = 4578^2 + 560^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 54069 + ... + 54460.

Almost surely, 2^21271684 is an apocalyptic number.

It is an amenable number.

21271684 is an abundant number, since it is smaller than the sum of its proper divisors (22031786).

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

21271684 is a wasteful number, since it uses less digits than its factorization.

21271684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108547 (or 108538 counting only the distinct ones).

The product of its digits is 5376, while the sum is 31.

The square root of 21271684 is about 4612.1235889772. The cubic root of 21271684 is about 277.0770941039.

Adding to 21271684 its reverse (48617212), we get a palindrome (69888896).

The spelling of 21271684 in words is "twenty-one million, two hundred seventy-one thousand, six hundred eighty-four".