21101880 has 64 divisors (see below), whose sum is σ = 64864800. Its totient is φ = 5488640.

The previous prime is 21101869. The next prime is 21101887. The reversal of 21101880 is 8810112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2776 + ... + 7064.

Almost surely, 2^21101880 is an apocalyptic number.

21101880 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 21101880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32432400).

21101880 is an abundant number, since it is smaller than the sum of its proper divisors (43762920).

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

21101880 is a wasteful number, since it uses less digits than its factorization.

21101880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4344 (or 4340 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 21101880 is about 4593.6782647460. The cubic root of 21101880 is about 276.3378555286.

Adding to 21101880 its reverse (8810112), we get a palindrome (29911992).

The spelling of 21101880 in words is "twenty-one million, one hundred one thousand, eight hundred eighty".