40571981 has 4 divisors (see below), whose sum is σ = 40584732. Its totient is φ = 40559232.

The previous prime is 40571969. The next prime is 40571987. The reversal of 40571981 is 18917504.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 8649481 + 31922500 = 2941^2 + 5650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40571981 is a prime.

It is a super-2 number, since 2×40571981² = 3292171284528722, which contains 22 as substring.

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 (40571987) 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, 2795 + ... + 9431.

It is an arithmetic number, because the mean of its divisors is an integer number (10146183).

Almost surely, 2^40571981 is an apocalyptic number.

It is an amenable number.

40571981 is a deficient number, since it is larger than the sum of its proper divisors (12751).

40571981 is an equidigital number, since it uses as much as digits as its factorization.

40571981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12750.

The product of its (nonzero) digits is 10080, while the sum is 35.

The square root of 40571981 is about 6369.6138815473. The cubic root of 40571981 is about 343.6176034047.

The spelling of 40571981 in words is "forty million, five hundred seventy-one thousand, nine hundred eighty-one".