21100080 has 40 divisors (see below), whose sum is σ = 65410992. Its totient is φ = 5626624.

The previous prime is 21100069. The next prime is 21100087. The reversal of 21100080 is 8000112.

It is a happy number.

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

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (21100087) 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 7 ways as a sum of consecutive naturals, for example, 43719 + ... + 44198.

Almost surely, 2^21100080 is an apocalyptic number.

21100080 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100080 is an abundant number, since it is smaller than the sum of its proper divisors (44310912).

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

21100080 is a wasteful number, since it uses less digits than its factorization.

21100080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87933 (or 87927 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 21100080 is about 4593.4823391410. The cubic root of 21100080 is about 276.3299980568.

Adding to 21100080 its reverse (8000112), we get a palindrome (29100192).

The spelling of 21100080 in words is "twenty-one million, one hundred thousand, eighty".