21409312 has 24 divisors (see below), whose sum is σ = 42287616. Its totient is φ = 10669632.

The previous prime is 21409303. The next prime is 21409321. The reversal of 21409312 is 21390412.

It is an interprime number because it is at equal distance from previous prime (21409303) and next prime (21409321).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10833 + ... + 12655.

It is an arithmetic number, because the mean of its divisors is an integer number (1761984).

Almost surely, 2^21409312 is an apocalyptic number.

It is an amenable number.

21409312 is a deficient number, since it is larger than the sum of its proper divisors (20878304).

21409312 is a wasteful number, since it uses less digits than its factorization.

21409312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2200 (or 2192 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21409312 is about 4627.0197751901. The cubic root of 21409312 is about 277.6733737894.

Adding to 21409312 its reverse (21390412), we get a palindrome (42799724).

The spelling of 21409312 in words is "twenty-one million, four hundred nine thousand, three hundred twelve".