21000546 has 48 divisors (see below), whose sum is σ = 53936064. Its totient is φ = 5999184.

The previous prime is 21000533. The next prime is 21000557. The reversal of 21000546 is 64500012.

It is a happy number.

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 316 + ... + 6488.

It is an arithmetic number, because the mean of its divisors is an integer number (1123668).

Almost surely, 2^21000546 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21000546, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26968032).

21000546 is an abundant number, since it is smaller than the sum of its proper divisors (32935518).

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

21000546 is an equidigital number, since it uses as much as digits as its factorization.

21000546 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6197 (or 6185 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21000546 is about 4582.6352680527. The cubic root of 21000546 is about 275.8948086850.

Adding to 21000546 its reverse (64500012), we get a palindrome (85500558).

The spelling of 21000546 in words is "twenty-one million, five hundred forty-six", and thus it is an aban number.