40207721 has 2 divisors, whose sum is σ = 40207722. Its totient is φ = 40207720.

The previous prime is 40207697. The next prime is 40207753. The reversal of 40207721 is 12770204.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 34351321 + 5856400 = 5861^2 + 2420^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-40207721 is a prime.

It is not a weakly prime, because it can be changed into another prime (40207621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20103860 + 20103861.

It is an arithmetic number, because the mean of its divisors is an integer number (20103861).

Almost surely, 2^40207721 is an apocalyptic number.

It is an amenable number.

40207721 is a deficient number, since it is larger than the sum of its proper divisors (1).

40207721 is an equidigital number, since it uses as much as digits as its factorization.

40207721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 784, while the sum is 23.

The square root of 40207721 is about 6340.9558427732. The cubic root of 40207721 is about 342.5861640533.

Adding to 40207721 its reverse (12770204), we get a palindrome (52977925).

The spelling of 40207721 in words is "forty million, two hundred seven thousand, seven hundred twenty-one".