40205981 has 2 divisors, whose sum is σ = 40205982. Its totient is φ = 40205980.

The previous prime is 40205941. The next prime is 40205987. The reversal of 40205981 is 18950204.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29539225 + 10666756 = 5435^2 + 3266^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40205981 is a prime.

It is a super-2 number, since 2×40205981² = 3233041816344722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40205987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20102990 + 20102991.

It is an arithmetic number, because the mean of its divisors is an integer number (20102991).

Almost surely, 2^40205981 is an apocalyptic number.

It is an amenable number.

40205981 is a deficient number, since it is larger than the sum of its proper divisors (1).

40205981 is an equidigital number, since it uses as much as digits as its factorization.

40205981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 40205981 is about 6340.8186379994. The cubic root of 40205981 is about 342.5812221458.

It can be divided in two parts, 4020 and 5981, that added together give a palindrome (10001).

The spelling of 40205981 in words is "forty million, two hundred five thousand, nine hundred eighty-one".