42517721 has 4 divisors (see below), whose sum is σ = 43056000. Its totient is φ = 41979444.

The previous prime is 42517693. The next prime is 42517723. The reversal of 42517721 is 12771524.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42517721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (42517723) 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, 269021 + ... + 269178.

It is an arithmetic number, because the mean of its divisors is an integer number (10764000).

Almost surely, 2^42517721 is an apocalyptic number.

It is an amenable number.

42517721 is a deficient number, since it is larger than the sum of its proper divisors (538279).

42517721 is an equidigital number, since it uses as much as digits as its factorization.

42517721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538278.

The product of its digits is 3920, while the sum is 29.

The square root of 42517721 is about 6520.5614022107. The cubic root of 42517721 is about 349.0250992477.

The spelling of 42517721 in words is "forty-two million, five hundred seventeen thousand, seven hundred twenty-one".