21859906 has 16 divisors (see below), whose sum is σ = 33436800. Its totient is φ = 10716160.

The previous prime is 21859897. The next prime is 21859907. The reversal of 21859906 is 60995812.

It is not an unprimeable number, because it can be changed into a prime (21859907) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 36195 + ... + 36793.

It is an arithmetic number, because the mean of its divisors is an integer number (2089800).

Almost surely, 2^21859906 is an apocalyptic number.

21859906 is a deficient number, since it is larger than the sum of its proper divisors (11576894).

21859906 is a wasteful number, since it uses less digits than its factorization.

21859906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 929.

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 21859906 is about 4675.4578385437. The cubic root of 21859906 is about 279.6078950399.

The spelling of 21859906 in words is "twenty-one million, eight hundred fifty-nine thousand, nine hundred six".