21115000 has 80 divisors (see below), whose sum is σ = 51171120. Its totient is φ = 8160000.

The previous prime is 21114997. The next prime is 21115007. The reversal of 21115000 is 51112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115007) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 204949 + ... + 205051.

It is an arithmetic number, because the mean of its divisors is an integer number (639639).

Almost surely, 2^21115000 is an apocalyptic number.

21115000 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 21115000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25585560).

21115000 is an abundant number, since it is smaller than the sum of its proper divisors (30056120).

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

21115000 is a wasteful number, since it uses less digits than its factorization.

21115000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170 (or 151 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 10.

The square root of 21115000 is about 4595.1060923552. The cubic root of 21115000 is about 276.3951142742.

Adding to 21115000 its reverse (51112), we get a palindrome (21166112).

The spelling of 21115000 in words is "twenty-one million, one hundred fifteen thousand".