21506480 has 40 divisors (see below), whose sum is σ = 52638000. Its totient is φ = 8149248.

The previous prime is 21506473. The next prime is 21506483. The reversal of 21506480 is 8460512.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (21506483) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5555 + ... + 8594.

It is an arithmetic number, because the mean of its divisors is an integer number (1315950).

Almost surely, 2^21506480 is an apocalyptic number.

21506480 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21506480 is an abundant number, since it is smaller than the sum of its proper divisors (31131520).

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

21506480 is a wasteful number, since it uses less digits than its factorization.

21506480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14181 (or 14175 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 21506480 is about 4637.5079514757. The cubic root of 21506480 is about 278.0928213413.

Adding to 21506480 its reverse (8460512), we get a palindrome (29966992).

The spelling of 21506480 in words is "twenty-one million, five hundred six thousand, four hundred eighty".