21519720 has 144 divisors (see below), whose sum is σ = 73759140. Its totient is φ = 5440512.

The previous prime is 21519713. The next prime is 21519721. The reversal of 21519720 is 2791512.

It can be written as a sum of positive squares in 2 ways, for example, as 18301284 + 3218436 = 4278^2 + 1794^2 .

It is not an unprimeable number, because it can be changed into a prime (21519721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 190384 + ... + 190496.

Almost surely, 2^21519720 is an apocalyptic number.

21519720 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 21519720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36879570).

21519720 is an abundant number, since it is smaller than the sum of its proper divisors (52239420).

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

21519720 is a wasteful number, since it uses less digits than its factorization.

21519720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176 (or 146 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21519720 is about 4638.9352226562. The cubic root of 21519720 is about 278.1498769147.

The spelling of 21519720 in words is "twenty-one million, five hundred nineteen thousand, seven hundred twenty".