21609850 has 24 divisors (see below), whose sum is σ = 41284188. Its totient is φ = 8409600.

The previous prime is 21609817. The next prime is 21609851. The reversal of 21609850 is 5890612.

It can be written as a sum of positive squares in 6 ways, for example, as 12723489 + 8886361 = 3567^2 + 2981^2 .

It is not an unprimeable number, because it can be changed into a prime (21609851) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3991 + ... + 7690.

Almost surely, 2^21609850 is an apocalyptic number.

21609850 is a deficient number, since it is larger than the sum of its proper divisors (19674338).

21609850 is a wasteful number, since it uses less digits than its factorization.

21609850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11730 (or 11725 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 21609850 is about 4648.6395859434. The cubic root of 21609850 is about 278.5376565928.

The spelling of 21609850 in words is "twenty-one million, six hundred nine thousand, eight hundred fifty".