21508232 has 8 divisors (see below), whose sum is σ = 40327950. Its totient is φ = 10754112.

The previous prime is 21508229. The next prime is 21508237. The reversal of 21508232 is 23280512.

It can be written as a sum of positive squares in only one way, i.e., 20921476 + 586756 = 4574^2 + 766^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21508198 and 21508207.

It is not an unprimeable number, because it can be changed into a prime (21508237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1344257 + ... + 1344272.

Almost surely, 2^21508232 is an apocalyptic number.

It is an amenable number.

21508232 is a deficient number, since it is larger than the sum of its proper divisors (18819718).

21508232 is a wasteful number, since it uses less digits than its factorization.

21508232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2688535 (or 2688531 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21508232 is about 4637.6968421836. The cubic root of 21508232 is about 278.1003726374.

Adding to 21508232 its reverse (23280512), we get a palindrome (44788744).

The spelling of 21508232 in words is "twenty-one million, five hundred eight thousand, two hundred thirty-two".