21165000 has 160 divisors (see below), whose sum is σ = 70852320. Its totient is φ = 5248000.

The previous prime is 21164989. The next prime is 21165007. The reversal of 21165000 is 56112.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is not an unprimeable number, because it can be changed into a prime (21165007) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 254959 + ... + 255041.

It is an arithmetic number, because the mean of its divisors is an integer number (442827).

Almost surely, 2^21165000 is an apocalyptic number.

21165000 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 21165000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35426160).

21165000 is an abundant number, since it is smaller than the sum of its proper divisors (49687320).

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

21165000 is a wasteful number, since it uses less digits than its factorization.

21165000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21165000 is about 4600.5434461594. The cubic root of 21165000 is about 276.6131087760.

The spelling of 21165000 in words is "twenty-one million, one hundred sixty-five thousand".