42721985 has 4 divisors (see below), whose sum is σ = 51266388. Its totient is φ = 34177584.

The previous prime is 42721981. The next prime is 42722027. The reversal of 42721985 is 58912724.

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 22972849 + 19749136 = 4793^2 + 4444^2 .

It is a cyclic number.

It is not a de Polignac number, because 42721985 - 2² = 42721981 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42721981) 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, 4272194 + ... + 4272203.

It is an arithmetic number, because the mean of its divisors is an integer number (12816597).

Almost surely, 2^42721985 is an apocalyptic number.

It is an amenable number.

42721985 is a deficient number, since it is larger than the sum of its proper divisors (8544403).

42721985 is an equidigital number, since it uses as much as digits as its factorization.

42721985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8544402.

The product of its digits is 40320, while the sum is 38.

The square root of 42721985 is about 6536.2057036174. The cubic root of 42721985 is about 349.5831363493.

The spelling of 42721985 in words is "forty-two million, seven hundred twenty-one thousand, nine hundred eighty-five".