21527440 has 80 divisors (see below), whose sum is σ = 57853440. Its totient is φ = 7362560.

The previous prime is 21527417. The next prime is 21527459. The reversal of 21527440 is 4472512.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 14241 + ... + 15679.

It is an arithmetic number, because the mean of its divisors is an integer number (723168).

Almost surely, 2^21527440 is an apocalyptic number.

21527440 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 21527440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28926720).

21527440 is an abundant number, since it is smaller than the sum of its proper divisors (36326000).

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

21527440 is a wasteful number, since it uses less digits than its factorization.

21527440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1480 (or 1474 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 21527440 is about 4639.7672355410. The cubic root of 21527440 is about 278.1831341678.

Adding to 21527440 its reverse (4472512), we get a palindrome (25999952).

The spelling of 21527440 in words is "twenty-one million, five hundred twenty-seven thousand, four hundred forty".