21071850 has 48 divisors (see below), whose sum is σ = 53166240. Its totient is φ = 5521600.

The previous prime is 21071837. The next prime is 21071851. The reversal of 21071850 is 5817012.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21071850.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21071851) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7660 + ... + 10040.

It is an arithmetic number, because the mean of its divisors is an integer number (1107630).

Almost surely, 2^21071850 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21071850, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26583120).

21071850 is an abundant number, since it is smaller than the sum of its proper divisors (32094390).

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

21071850 is a wasteful number, since it uses less digits than its factorization.

21071850 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2455 (or 2450 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 21071850 is about 4590.4084785561. The cubic root of 21071850 is about 276.2067082027.

Adding to 21071850 its reverse (5817012), we get a palindrome (26888862).

The spelling of 21071850 in words is "twenty-one million, seventy-one thousand, eight hundred fifty".