21541520 has 160 divisors (see below), whose sum is σ = 67495680. Its totient is φ = 6174720.

The previous prime is 21541517. The next prime is 21541537. The reversal of 21541520 is 2514512.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21541492 and 21541501.

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, 79946 + ... + 80214.

It is an arithmetic number, because the mean of its divisors is an integer number (421848).

Almost surely, 2^21541520 is an apocalyptic number.

21541520 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 21541520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33747840).

21541520 is an abundant number, since it is smaller than the sum of its proper divisors (45954160).

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

21541520 is a wasteful number, since it uses less digits than its factorization.

21541520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313 (or 307 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 21541520 is about 4641.2843050173. The cubic root of 21541520 is about 278.2437694145.

The spelling of 21541520 in words is "twenty-one million, five hundred forty-one thousand, five hundred twenty".