42641721 has 10 divisors (see below), whose sum is σ = 63699482. Its totient is φ = 28427760.

The previous prime is 42641717. The next prime is 42641761. The reversal of 42641721 is 12714624.

It can be written as a sum of positive squares in only one way, i.e., 39237696 + 3404025 = 6264^2 + 1845^2 .

It is not a de Polignac number, because 42641721 - 2² = 42641717 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42641761) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 263140 + ... + 263301.

Almost surely, 2^42641721 is an apocalyptic number.

It is an amenable number.

42641721 is a deficient number, since it is larger than the sum of its proper divisors (21057761).

42641721 is an equidigital number, since it uses as much as digits as its factorization.

42641721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526453 (or 526444 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 42641721 is about 6530.0628634034. The cubic root of 42641721 is about 349.3640724712.

The spelling of 42641721 in words is "forty-two million, six hundred forty-one thousand, seven hundred twenty-one".