21261480 has 64 divisors (see below), whose sum is σ = 65007360. Its totient is φ = 5561088.

The previous prime is 21261463. The next prime is 21261481. The reversal of 21261480 is 8416212.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21261480.

It is not an unprimeable number, because it can be changed into a prime (21261481) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4689 + ... + 8031.

It is an arithmetic number, because the mean of its divisors is an integer number (1015740).

Almost surely, 2^21261480 is an apocalyptic number.

21261480 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21261480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32503680).

21261480 is an abundant number, since it is smaller than the sum of its proper divisors (43745880).

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

21261480 is a wasteful number, since it uses less digits than its factorization.

21261480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3410 (or 3406 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 21261480 is about 4611.0172413471. The cubic root of 21261480 is about 277.0327825068.

Adding to 21261480 its reverse (8416212), we get a palindrome (29677692).

The spelling of 21261480 in words is "twenty-one million, two hundred sixty-one thousand, four hundred eighty".