21859989 has 8 divisors (see below), whose sum is σ = 29185920. Its totient is φ = 14553696.

The previous prime is 21859987. The next prime is 21860057. The reversal of 21859989 is 98995812.

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

It is not a de Polignac number, because 21859989 - 2¹ = 21859987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21859987) 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 7 ways as a sum of consecutive naturals, for example, 2077 + ... + 6930.

It is an arithmetic number, because the mean of its divisors is an integer number (3648240).

Almost surely, 2^21859989 is an apocalyptic number.

It is an amenable number.

21859989 is a deficient number, since it is larger than the sum of its proper divisors (7325931).

21859989 is an equidigital number, since it uses as much as digits as its factorization.

21859989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9819.

The product of its digits is 466560, while the sum is 51.

The square root of 21859989 is about 4675.4667146714. The cubic root of 21859989 is about 279.6082489211.

The spelling of 21859989 in words is "twenty-one million, eight hundred fifty-nine thousand, nine hundred eighty-nine".