21130785 has 48 divisors (see below), whose sum is σ = 40452048. Its totient is φ = 10137600.

The previous prime is 21130783. The next prime is 21130801. The reversal of 21130785 is 58703112.

It can be written as a sum of positive squares in 8 ways, for example, as 9290304 + 11840481 = 3048^2 + 3441^2 .

It is not a de Polignac number, because 21130785 - 2¹ = 21130783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130783) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 23545 + ... + 24425.

It is an arithmetic number, because the mean of its divisors is an integer number (842751).

Almost surely, 2^21130785 is an apocalyptic number.

It is an amenable number.

21130785 is a deficient number, since it is larger than the sum of its proper divisors (19321263).

21130785 is a wasteful number, since it uses less digits than its factorization.

21130785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 946 (or 943 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 21130785 is about 4596.8233596692. The cubic root of 21130785 is about 276.4639722762.

Adding to 21130785 its reverse (58703112), we get a palindrome (79833897).

The spelling of 21130785 in words is "twenty-one million, one hundred thirty thousand, seven hundred eighty-five".