21687850 has 24 divisors (see below), whose sum is σ = 42095520. Its totient is φ = 8297520.

The previous prime is 21687803. The next prime is 21687857. The reversal of 21687850 is 5878612.

It is not an unprimeable number, because it can be changed into a prime (21687857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8280 + ... + 10579.

It is an arithmetic number, because the mean of its divisors is an integer number (1753980).

Almost surely, 2^21687850 is an apocalyptic number.

21687850 is a deficient number, since it is larger than the sum of its proper divisors (20407670).

21687850 is a wasteful number, since it uses less digits than its factorization.

21687850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18894 (or 18889 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 21687850 is about 4657.0215803666. The cubic root of 21687850 is about 278.8723781794.

The spelling of 21687850 in words is "twenty-one million, six hundred eighty-seven thousand, eight hundred fifty".