42309661 has 4 divisors (see below), whose sum is σ = 43003324. Its totient is φ = 41616000.

The previous prime is 42309649. The next prime is 42309671. The reversal of 42309661 is 16690324.

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 7322436 + 34987225 = 2706^2 + 5915^2 .

It is a cyclic number.

It is not a de Polignac number, because 42309661 - 2¹⁷ = 42178589 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 (42309671) 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, 346740 + ... + 346861.

It is an arithmetic number, because the mean of its divisors is an integer number (10750831).

Almost surely, 2^42309661 is an apocalyptic number.

It is an amenable number.

42309661 is a deficient number, since it is larger than the sum of its proper divisors (693663).

42309661 is an equidigital number, since it uses as much as digits as its factorization.

42309661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 693662.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 42309661 is about 6504.5876887010. The cubic root of 42309661 is about 348.4548512383.

Adding to 42309661 its reverse (16690324), we get a palindrome (58999985).

The spelling of 42309661 in words is "forty-two million, three hundred nine thousand, six hundred sixty-one".