42784721 has 4 divisors (see below), whose sum is σ = 48896832. Its totient is φ = 36672612.

The previous prime is 42784697. The next prime is 42784723. The reversal of 42784721 is 12748724.

It is a happy number.

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-42784721 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 (42784723) 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, 3056045 + ... + 3056058.

It is an arithmetic number, because the mean of its divisors is an integer number (12224208).

Almost surely, 2^42784721 is an apocalyptic number.

It is an amenable number.

42784721 is a deficient number, since it is larger than the sum of its proper divisors (6112111).

42784721 is an equidigital number, since it uses as much as digits as its factorization.

42784721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6112110.

The product of its digits is 25088, while the sum is 35.

The square root of 42784721 is about 6541.0030576357. The cubic root of 42784721 is about 349.7541702339.

The spelling of 42784721 in words is "forty-two million, seven hundred eighty-four thousand, seven hundred twenty-one".