42817821 has 8 divisors (see below), whose sum is σ = 57645120. Its totient is φ = 28267872.

The previous prime is 42817787. The next prime is 42817823. The reversal of 42817821 is 12871824.

It is a happy number.

42817821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 42817821 - 2⁹ = 42817309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42817823) 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, 68976 + ... + 69593.

It is an arithmetic number, because the mean of its divisors is an integer number (7205640).

Almost surely, 2^42817821 is an apocalyptic number.

It is an amenable number.

42817821 is a deficient number, since it is larger than the sum of its proper divisors (14827299).

42817821 is a wasteful number, since it uses less digits than its factorization.

42817821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138675.

The product of its digits is 7168, while the sum is 33.

The square root of 42817821 is about 6543.5327614371. The cubic root of 42817821 is about 349.8443416674.

The spelling of 42817821 in words is "forty-two million, eight hundred seventeen thousand, eight hundred twenty-one".