4021581 has 4 divisors (see below), whose sum is σ = 5362112. Its totient is φ = 2681052.

The previous prime is 4021579. The next prime is 4021601. The reversal of 4021581 is 1851204.

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 not a de Polignac number, because 4021581 - 2¹ = 4021579 is a prime.

It is a super-2 number, since 2×4021581² = 32346227479122, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4021531) 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, 670261 + ... + 670266.

It is an arithmetic number, because the mean of its divisors is an integer number (1340528).

Almost surely, 2^4021581 is an apocalyptic number.

It is an amenable number.

4021581 is a deficient number, since it is larger than the sum of its proper divisors (1340531).

4021581 is a wasteful number, since it uses less digits than its factorization.

4021581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1340530.

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 4021581 is about 2005.3879923845. The cubic root of 4021581 is about 159.0250741675.

Adding to 4021581 its reverse (1851204), we get a palindrome (5872785).

The spelling of 4021581 in words is "four million, twenty-one thousand, five hundred eighty-one".