21115080 has 320 divisors, whose sum is σ = 87120000. Its totient is φ = 4572288.

The previous prime is 21115063. The next prime is 21115091. The reversal of 21115080 is 8051112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1111311 + ... + 1111329.

It is an arithmetic number, because the mean of its divisors is an integer number (272250).

Almost surely, 2^21115080 is an apocalyptic number.

21115080 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 21115080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43560000).

21115080 is an abundant number, since it is smaller than the sum of its proper divisors (66004920).

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

21115080 is a wasteful number, since it uses less digits than its factorization.

21115080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63 (or 36 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 21115080 is about 4595.1147972602. The cubic root of 21115080 is about 276.3954633401.

Adding to 21115080 its reverse (8051112), we get a palindrome (29166192).

The spelling of 21115080 in words is "twenty-one million, one hundred fifteen thousand, eighty".