21420312 has 16 divisors (see below), whose sum is σ = 53550840. Its totient is φ = 7140096.

The previous prime is 21420293. The next prime is 21420331. The reversal of 21420312 is 21302412.

It is an interprime number because it is at equal distance from previous prime (21420293) and next prime (21420331).

It is a junction number, because it is equal to n+sod(n) for n = 21420291 and 21420300.

It is a congruent number.

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 in 3 ways as a sum of consecutive naturals, for example, 446233 + ... + 446280.

Almost surely, 2^21420312 is an apocalyptic number.

It is an amenable number.

21420312 is an abundant number, since it is smaller than the sum of its proper divisors (32130528).

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

21420312 is a wasteful number, since it uses less digits than its factorization.

21420312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 892522 (or 892518 counting only the distinct ones).

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

The square root of 21420312 is about 4628.2082926333. The cubic root of 21420312 is about 277.7209213884.

Adding to 21420312 its reverse (21302412), we get a palindrome (42722724).

The spelling of 21420312 in words is "twenty-one million, four hundred twenty thousand, three hundred twelve".