21315206 has 16 divisors (see below), whose sum is σ = 34974720. Its totient is φ = 9662280.

The previous prime is 21315187. The next prime is 21315211. The reversal of 21315206 is 60251312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8555 + ... + 10761.

It is an arithmetic number, because the mean of its divisors is an integer number (2185920).

Almost surely, 2^21315206 is an apocalyptic number.

21315206 is a deficient number, since it is larger than the sum of its proper divisors (13659514).

21315206 is a wasteful number, since it uses less digits than its factorization.

21315206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2659.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21315206 is about 4616.8393950840. The cubic root of 21315206 is about 277.2659325365.

Adding to 21315206 its reverse (60251312), we get a palindrome (81566518).

It can be divided in two parts, 2131 and 5206, that added together give a palindrome (7337).

The spelling of 21315206 in words is "twenty-one million, three hundred fifteen thousand, two hundred six".