21609986 has 8 divisors (see below), whose sum is σ = 32871744. Its totient is φ = 10652740.

The previous prime is 21609977. The next prime is 21610003. The reversal of 21609986 is 68990612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 75950 + ... + 76233.

It is an arithmetic number, because the mean of its divisors is an integer number (4108968).

Almost surely, 2^21609986 is an apocalyptic number.

21609986 is a deficient number, since it is larger than the sum of its proper divisors (11261758).

21609986 is a wasteful number, since it uses less digits than its factorization.

21609986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152256.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 21609986 is about 4648.6542138559. The cubic root of 21609986 is about 278.5382409103.

The spelling of 21609986 in words is "twenty-one million, six hundred nine thousand, nine hundred eighty-six".