40017721 has 2 divisors, whose sum is σ = 40017722. Its totient is φ = 40017720.

The previous prime is 40017713. The next prime is 40017751. The reversal of 40017721 is 12771004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 33767721 + 6250000 = 5811^2 + 2500^2 .

It is a cyclic number.

It is not a de Polignac number, because 40017721 - 2³ = 40017713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 40017692 and 40017701.

It is not a weakly prime, because it can be changed into another prime (40017701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20008860 + 20008861.

It is an arithmetic number, because the mean of its divisors is an integer number (20008861).

Almost surely, 2^40017721 is an apocalyptic number.

It is an amenable number.

40017721 is a deficient number, since it is larger than the sum of its proper divisors (1).

40017721 is an equidigital number, since it uses as much as digits as its factorization.

40017721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 40017721 is about 6325.9561332655. The cubic root of 40017721 is about 342.0456860186.

Adding to 40017721 its reverse (12771004), we get a palindrome (52788725).

The spelling of 40017721 in words is "forty million, seventeen thousand, seven hundred twenty-one".