20909218 has 32 divisors (see below), whose sum is σ = 37231488. Its totient is φ = 8697600.

The previous prime is 20909209. The next prime is 20909281. The reversal of 20909218 is 81290902.

20909218 = 237² + 238² + ... + 423².

It is a self number, because there is not a number n which added to its sum of digits gives 20909218.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13083 + ... + 14593.

It is an arithmetic number, because the mean of its divisors is an integer number (1163484).

Almost surely, 2^20909218 is an apocalyptic number.

20909218 is a deficient number, since it is larger than the sum of its proper divisors (16322270).

20909218 is a wasteful number, since it uses less digits than its factorization.

20909218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1578.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 20909218 is about 4572.6598386497. The cubic root of 20909218 is about 275.4942867910.

The spelling of 20909218 in words is "twenty million, nine hundred nine thousand, two hundred eighteen".