40216721 has 2 divisors, whose sum is σ = 40216722. Its totient is φ = 40216720.

The previous prime is 40216717. The next prime is 40216727. The reversal of 40216721 is 12761204.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 35760400 + 4456321 = 5980^2 + 2111^2 .

It is a cyclic number.

It is not a de Polignac number, because 40216721 - 2² = 40216717 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (40216727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20108360 + 20108361.

It is an arithmetic number, because the mean of its divisors is an integer number (20108361).

Almost surely, 2^40216721 is an apocalyptic number.

It is an amenable number.

40216721 is a deficient number, since it is larger than the sum of its proper divisors (1).

40216721 is an equidigital number, since it uses as much as digits as its factorization.

40216721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 40216721 is about 6341.6654752517. The cubic root of 40216721 is about 342.6117233686.

Adding to 40216721 its reverse (12761204), we get a palindrome (52977925).

The spelling of 40216721 in words is "forty million, two hundred sixteen thousand, seven hundred twenty-one".