21651232 has 12 divisors (see below), whose sum is σ = 42625926. Its totient is φ = 10825600.

The previous prime is 21651221. The next prime is 21651271. The reversal of 21651232 is 23215612.

It can be written as a sum of positive squares in only one way, i.e., 18974736 + 2676496 = 4356^2 + 1636^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 338269 + ... + 338332.

Almost surely, 2^21651232 is an apocalyptic number.

It is an amenable number.

21651232 is a deficient number, since it is larger than the sum of its proper divisors (20974694).

21651232 is an equidigital number, since it uses as much as digits as its factorization.

21651232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 676611 (or 676603 counting only the distinct ones).

The product of its digits is 720, while the sum is 22.

The square root of 21651232 is about 4653.0884367267. The cubic root of 21651232 is about 278.7153393865.

Adding to 21651232 its reverse (23215612), we get a palindrome (44866844).

The spelling of 21651232 in words is "twenty-one million, six hundred fifty-one thousand, two hundred thirty-two".