21312232 has 8 divisors (see below), whose sum is σ = 39960450. Its totient is φ = 10656112.

The previous prime is 21312229. The next prime is 21312233. The reversal of 21312232 is 23221312.

It can be written as a sum of positive squares in only one way, i.e., 12348196 + 8964036 = 3514^2 + 2994^2 .

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

It is a super-2 number, since 2×21312232² = 908422465643648, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21312233) 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 as a sum of consecutive naturals, namely, 1332007 + ... + 1332022.

Almost surely, 2^21312232 is an apocalyptic number.

It is an amenable number.

21312232 is a deficient number, since it is larger than the sum of its proper divisors (18648218).

21312232 is a wasteful number, since it uses less digits than its factorization.

21312232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2664035 (or 2664031 counting only the distinct ones).

The product of its digits is 144, while the sum is 16.

The square root of 21312232 is about 4616.5173020362. The cubic root of 21312232 is about 277.2530367782.

Adding to 21312232 its reverse (23221312), we get a palindrome (44533544).

The spelling of 21312232 in words is "twenty-one million, three hundred twelve thousand, two hundred thirty-two".