21289986 has 16 divisors (see below), whose sum is σ = 47311200. Its totient is φ = 7096644.

The previous prime is 21289981. The next prime is 21289993. The reversal of 21289986 is 68998212.

It is not an unprimeable number, because it can be changed into a prime (21289981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197076 + ... + 197183.

It is an arithmetic number, because the mean of its divisors is an integer number (2956950).

Almost surely, 2^21289986 is an apocalyptic number.

21289986 is an abundant number, since it is smaller than the sum of its proper divisors (26021214).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21289986 is a wasteful number, since it uses less digits than its factorization.

21289986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394270 (or 394264 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 21289986 is about 4614.1072809375. The cubic root of 21289986 is about 277.1565363537.

The spelling of 21289986 in words is "twenty-one million, two hundred eighty-nine thousand, nine hundred eighty-six".