40000721 has 2 divisors, whose sum is σ = 40000722. Its totient is φ = 40000720.

The previous prime is 40000717. The next prime is 40000729. The reversal of 40000721 is 12700004.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38887696 + 1113025 = 6236^2 + 1055^2 .

It is a cyclic number.

It is not a de Polignac number, because 40000721 - 2² = 40000717 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 40000696 and 40000705.

It is not a weakly prime, because it can be changed into another prime (40000729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20000360 + 20000361.

It is an arithmetic number, because the mean of its divisors is an integer number (20000361).

Almost surely, 2^40000721 is an apocalyptic number.

It is an amenable number.

40000721 is a deficient number, since it is larger than the sum of its proper divisors (1).

40000721 is an equidigital number, since it uses as much as digits as its factorization.

40000721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 56, while the sum is 14.

The square root of 40000721 is about 6324.6123201347. The cubic root of 40000721 is about 341.9972441441.

Adding to 40000721 its reverse (12700004), we get a palindrome (52700725).

The spelling of 40000721 in words is "forty million, seven hundred twenty-one", and thus it is an aban number.