42821689 has 4 divisors (see below), whose sum is σ = 43200756. Its totient is φ = 42442624.

The previous prime is 42821683. The next prime is 42821711. The reversal of 42821689 is 98612824.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4443664 + 38378025 = 2108^2 + 6195^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42821689 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42821683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 189364 + ... + 189589.

It is an arithmetic number, because the mean of its divisors is an integer number (10800189).

Almost surely, 2^42821689 is an apocalyptic number.

It is an amenable number.

42821689 is a deficient number, since it is larger than the sum of its proper divisors (379067).

42821689 is a wasteful number, since it uses less digits than its factorization.

42821689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 379066.

The product of its digits is 55296, while the sum is 40.

The square root of 42821689 is about 6543.8283137625. The cubic root of 42821689 is about 349.8548758884.

The spelling of 42821689 in words is "forty-two million, eight hundred twenty-one thousand, six hundred eighty-nine".