21205702 has 16 divisors (see below), whose sum is σ = 36426240. Its totient is φ = 9069768.

The previous prime is 21205687. The next prime is 21205703. The reversal of 21205702 is 20750212.

It is a self number, because there is not a number n which added to its sum of digits gives 21205702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7443 + ... + 9889.

It is an arithmetic number, because the mean of its divisors is an integer number (2276640).

Almost surely, 2^21205702 is an apocalyptic number.

21205702 is a deficient number, since it is larger than the sum of its proper divisors (15220538).

21205702 is a wasteful number, since it uses less digits than its factorization.

21205702 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3075.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 21205702 is about 4604.9649292910. The cubic root of 21205702 is about 276.7903116632.

Adding to 21205702 its reverse (20750212), we get a palindrome (41955914).

The spelling of 21205702 in words is "twenty-one million, two hundred five thousand, seven hundred two".