21857973 has 8 divisors (see below), whose sum is σ = 29215200. Its totient is φ = 14536368.

The previous prime is 21857959. The next prime is 21857993. The reversal of 21857973 is 37975812.

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

It is not a de Polignac number, because 21857973 - 2¹⁶ = 21792437 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21857933) 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, 7438 + ... + 9951.

It is an arithmetic number, because the mean of its divisors is an integer number (3651900).

Almost surely, 2^21857973 is an apocalyptic number.

It is an amenable number.

21857973 is a deficient number, since it is larger than the sum of its proper divisors (7357227).

21857973 is a wasteful number, since it uses less digits than its factorization.

21857973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17811.

The product of its digits is 105840, while the sum is 42.

The square root of 21857973 is about 4675.2511162503. The cubic root of 21857973 is about 279.5996531931.

The spelling of 21857973 in words is "twenty-one million, eight hundred fifty-seven thousand, nine hundred seventy-three".