42013721 has 8 divisors (see below), whose sum is σ = 43534920. Its totient is φ = 40497408.

The previous prime is 42013717. The next prime is 42013729. The reversal of 42013721 is 12731024.

It can be written as a sum of positive squares in 4 ways, for example, as 9066121 + 32947600 = 3011^2 + 5740^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 42013721 - 2² = 42013717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42013693 and 42013702.

It is not an unprimeable number, because it can be changed into a prime (42013729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31745 + ... + 33041.

It is an arithmetic number, because the mean of its divisors is an integer number (5441865).

Almost surely, 2^42013721 is an apocalyptic number.

It is an amenable number.

42013721 is a deficient number, since it is larger than the sum of its proper divisors (1521199).

42013721 is a wasteful number, since it uses less digits than its factorization.

42013721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2443.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 42013721 is about 6481.7992100959. The cubic root of 42013721 is about 347.6405131940.

Adding to 42013721 its reverse (12731024), we get a palindrome (54744745).

It can be divided in two parts, 420 and 13721, that added together give a palindrome (14141).

The spelling of 42013721 in words is "forty-two million, thirteen thousand, seven hundred twenty-one".