21859916 has 12 divisors (see below), whose sum is σ = 41197632. Its totient is φ = 10089168.

The previous prime is 21859907. The next prime is 21859921. The reversal of 21859916 is 61995812.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 210140 + ... + 210243.

It is an arithmetic number, because the mean of its divisors is an integer number (3433136).

Almost surely, 2^21859916 is an apocalyptic number.

21859916 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21859916 is a deficient number, since it is larger than the sum of its proper divisors (19337716).

21859916 is a wasteful number, since it uses less digits than its factorization.

21859916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420400 (or 420398 counting only the distinct ones).

The product of its digits is 38880, while the sum is 41.

The square root of 21859916 is about 4675.4589079576. The cubic root of 21859916 is about 279.6079376763.

The spelling of 21859916 in words is "twenty-one million, eight hundred fifty-nine thousand, nine hundred sixteen".