42123409 has 4 divisors (see below), whose sum is σ = 42700516. Its totient is φ = 41546304.

The previous prime is 42123401. The next prime is 42123449. The reversal of 42123409 is 90432124.

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 27531009 + 14592400 = 5247^2 + 3820^2 .

It is a cyclic number.

It is not a de Polignac number, because 42123409 - 2³ = 42123401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42123401) 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, 288444 + ... + 288589.

It is an arithmetic number, because the mean of its divisors is an integer number (10675129).

Almost surely, 2^42123409 is an apocalyptic number.

It is an amenable number.

42123409 is a deficient number, since it is larger than the sum of its proper divisors (577107).

42123409 is an equidigital number, since it uses as much as digits as its factorization.

42123409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 577106.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 42123409 is about 6490.2549256558. The cubic root of 42123409 is about 347.9427863180.

The spelling of 42123409 in words is "forty-two million, one hundred twenty-three thousand, four hundred nine".