21486520 has 64 divisors (see below), whose sum is σ = 53913600. Its totient is φ = 7639680.

The previous prime is 21486467. The next prime is 21486523. The reversal of 21486520 is 2568412.

21486520 = 653² + 654² + ... + 699².

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21486523) 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, 20161 + ... + 21199.

It is an arithmetic number, because the mean of its divisors is an integer number (842400).

Almost surely, 2^21486520 is an apocalyptic number.

21486520 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 21486520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26956800).

21486520 is an abundant number, since it is smaller than the sum of its proper divisors (32427080).

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

21486520 is a wasteful number, since it uses less digits than its factorization.

21486520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1108 (or 1104 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 21486520 is about 4635.3554340525. The cubic root of 21486520 is about 278.0067627705.

It can be divided in two parts, 2148 and 6520, that added together give a palindrome (8668).

The spelling of 21486520 in words is "twenty-one million, four hundred eighty-six thousand, five hundred twenty".