21050705 has 24 divisors (see below), whose sum is σ = 28193256. Its totient is φ = 14999040.

The previous prime is 21050677. The next prime is 21050707. The reversal of 21050705 is 50705012.

It can be written as a sum of positive squares in 4 ways, for example, as 961 + 21049744 = 31^2 + 4588^2 .

It is not a de Polignac number, because 21050705 - 2¹⁰ = 21049681 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21050707) 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, 62297 + ... + 62633.

It is an arithmetic number, because the mean of its divisors is an integer number (1174719).

Almost surely, 2^21050705 is an apocalyptic number.

It is an amenable number.

21050705 is a deficient number, since it is larger than the sum of its proper divisors (7142551).

21050705 is a wasteful number, since it uses less digits than its factorization.

21050705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417 (or 386 counting only the distinct ones).

The product of its (nonzero) digits is 350, while the sum is 20.

The square root of 21050705 is about 4588.1047285344. The cubic root of 21050705 is about 276.1142887665.

Adding to 21050705 its reverse (50705012), we get a palindrome (71755717).

The spelling of 21050705 in words is "twenty-one million, fifty thousand, seven hundred five".