21312030 has 64 divisors (see below), whose sum is σ = 54286848. Its totient is φ = 5343360.

The previous prime is 21312023. The next prime is 21312059. The reversal of 21312030 is 3021312.

It is a happy number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21311997 and 21312015.

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 31 ways as a sum of consecutive naturals, for example, 46000 + ... + 46460.

It is an arithmetic number, because the mean of its divisors is an integer number (848232).

Almost surely, 2^21312030 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21312030, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27143424).

21312030 is an abundant number, since it is smaller than the sum of its proper divisors (32974818).

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

21312030 is a wasteful number, since it uses less digits than its factorization.

21312030 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 561.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21312030 is about 4616.4954240203. The cubic root of 21312030 is about 277.2521608291.

Adding to 21312030 its reverse (3021312), we get a palindrome (24333342).

The spelling of 21312030 in words is "twenty-one million, three hundred twelve thousand, thirty".