42021729 has 12 divisors (see below), whose sum is σ = 60966100. Its totient is φ = 27890784.

The previous prime is 42021703. The next prime is 42021743. The reversal of 42021729 is 92712024.

42021729 is a `hidden beast` number, since 420 + 217 + 29 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 39690000 + 2331729 = 6300^2 + 1527^2 .

It is not a de Polignac number, because 42021729 - 2¹⁶ = 41956193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42021779) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8134 + ... + 12255.

Almost surely, 2^42021729 is an apocalyptic number.

It is an amenable number.

42021729 is a deficient number, since it is larger than the sum of its proper divisors (18944371).

42021729 is a wasteful number, since it uses less digits than its factorization.

42021729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20624 (or 20621 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 42021729 is about 6482.4169103815. The cubic root of 42021729 is about 347.6625990611.

The spelling of 42021729 in words is "forty-two million, twenty-one thousand, seven hundred twenty-nine".