21261030 has 64 divisors (see below), whose sum is σ = 58821120. Its totient is φ = 4817664.

The previous prime is 21261029. The next prime is 21261041. The reversal of 21261030 is 3016212.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28401 + ... + 29139.

It is an arithmetic number, because the mean of its divisors is an integer number (919080).

Almost surely, 2^21261030 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21261030, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29410560).

21261030 is an abundant number, since it is smaller than the sum of its proper divisors (37560090).

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

21261030 is a wasteful number, since it uses less digits than its factorization.

21261030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 893.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 21261030 is about 4610.9684449148. The cubic root of 21261030 is about 277.0308280234.

Adding to 21261030 its reverse (3016212), we get a palindrome (24277242).

The spelling of 21261030 in words is "twenty-one million, two hundred sixty-one thousand, thirty".