21180080 has 80 divisors (see below), whose sum is σ = 51853824. Its totient is φ = 8037120.

The previous prime is 21180073. The next prime is 21180083. The reversal of 21180080 is 8008112.

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

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

It is not an unprimeable number, because it can be changed into a prime (21180083) 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 15 ways as a sum of consecutive naturals, for example, 161615 + ... + 161745.

Almost surely, 2^21180080 is an apocalyptic number.

21180080 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 21180080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25926912).

21180080 is an abundant number, since it is smaller than the sum of its proper divisors (30673744).

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

21180080 is a wasteful number, since it uses less digits than its factorization.

21180080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234 (or 228 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 21180080 is about 4602.1820911389. The cubic root of 21180080 is about 276.6787885207.

Adding to 21180080 its reverse (8008112), we get a palindrome (29188192).

The spelling of 21180080 in words is "twenty-one million, one hundred eighty thousand, eighty".