21240312 has 32 divisors (see below), whose sum is σ = 53491200. Its totient is φ = 7028064.

The previous prime is 21240311. The next prime is 21240313. The reversal of 21240312 is 21304212.

It is an interprime number because it is at equal distance from previous prime (21240311) and next prime (21240313).

It is a junction number, because it is equal to n+sod(n) for n = 21240291 and 21240300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240311) 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 in 7 ways as a sum of consecutive naturals, for example, 153 + ... + 6519.

It is an arithmetic number, because the mean of its divisors is an integer number (1671600).

Almost surely, 2^21240312 is an apocalyptic number.

It is an amenable number.

21240312 is an abundant number, since it is smaller than the sum of its proper divisors (32250888).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21240312 is a wasteful number, since it uses less digits than its factorization.

21240312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6515 (or 6511 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21240312 is about 4608.7212977137. The cubic root of 21240312 is about 276.9408137262.

Adding to 21240312 its reverse (21304212), we get a palindrome (42544524).

The spelling of 21240312 in words is "twenty-one million, two hundred forty thousand, three hundred twelve".