21313530 has 144 divisors (see below), whose sum is σ = 67223520. Its totient is φ = 4844448.

The previous prime is 21313493. The next prime is 21313531. The reversal of 21313530 is 3531312.

21313530 is a `hidden beast` number, since 2 + 131 + 3 + 530 = 666.

It is a super-2 number, since 2×21313530² = 908533122121800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21313531) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 118981 + ... + 119159.

It is an arithmetic number, because the mean of its divisors is an integer number (466830).

Almost surely, 2^21313530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21313530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33611760).

21313530 is an abundant number, since it is smaller than the sum of its proper divisors (45909990).

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

21313530 is a wasteful number, since it uses less digits than its factorization.

21313530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 270, while the sum is 18.

The square root of 21313530 is about 4616.6578820614. The cubic root of 21313530 is about 277.2586652694.

Adding to 21313530 its reverse (3531312), we get a palindrome (24844842).

The spelling of 21313530 in words is "twenty-one million, three hundred thirteen thousand, five hundred thirty".