42930821 has 4 divisors (see below), whose sum is σ = 42962700. Its totient is φ = 42898944.

The previous prime is 42930809. The next prime is 42930827. The reversal of 42930821 is 12803924.

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 8473921 + 34456900 = 2911^2 + 5870^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42930821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42930827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13826 + ... + 16643.

It is an arithmetic number, because the mean of its divisors is an integer number (10740675).

Almost surely, 2^42930821 is an apocalyptic number.

It is an amenable number.

42930821 is a deficient number, since it is larger than the sum of its proper divisors (31879).

42930821 is a wasteful number, since it uses less digits than its factorization.

42930821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31878.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 42930821 is about 6552.1615517324. The cubic root of 42930821 is about 350.1518280059.

The spelling of 42930821 in words is "forty-two million, nine hundred thirty thousand, eight hundred twenty-one".