21513030 has 128 divisors (see below), whose sum is σ = 65802240. Its totient is φ = 4371840.

The previous prime is 21513013. The next prime is 21513031. The reversal of 21513030 is 3031512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513031) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 154701 + ... + 154839.

It is an arithmetic number, because the mean of its divisors is an integer number (514080).

Almost surely, 2^21513030 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21513030, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32901120).

21513030 is an abundant number, since it is smaller than the sum of its proper divisors (44289210).

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

21513030 is a wasteful number, since it uses less digits than its factorization.

21513030 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234.

The product of its (nonzero) digits is 90, while the sum is 15.

The square root of 21513030 is about 4638.2140959641. The cubic root of 21513030 is about 278.1210504005.

Adding to 21513030 its reverse (3031512), we get a palindrome (24544542).

The spelling of 21513030 in words is "twenty-one million, five hundred thirteen thousand, thirty".