21440312 has 8 divisors (see below), whose sum is σ = 40200600. Its totient is φ = 10720152.

The previous prime is 21440291. The next prime is 21440317. The reversal of 21440312 is 21304412.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21440317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1340012 + ... + 1340027.

It is an arithmetic number, because the mean of its divisors is an integer number (5025075).

Almost surely, 2^21440312 is an apocalyptic number.

It is an amenable number.

21440312 is a deficient number, since it is larger than the sum of its proper divisors (18760288).

21440312 is a wasteful number, since it uses less digits than its factorization.

21440312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2680045 (or 2680041 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21440312 is about 4630.3684518621. The cubic root of 21440312 is about 277.8073298811.

Adding to 21440312 its reverse (21304412), we get a palindrome (42744724).

The spelling of 21440312 in words is "twenty-one million, four hundred forty thousand, three hundred twelve".