40242721 has 2 divisors, whose sum is σ = 40242722. Its totient is φ = 40242720.

The previous prime is 40242707. The next prime is 40242731. The reversal of 40242721 is 12724204.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 24750625 + 15492096 = 4975^2 + 3936^2 .

It is a cyclic number.

It is not a de Polignac number, because 40242721 - 2¹⁹ = 39718433 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 40242692 and 40242701.

It is not a weakly prime, because it can be changed into another prime (40242701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20121360 + 20121361.

It is an arithmetic number, because the mean of its divisors is an integer number (20121361).

Almost surely, 2^40242721 is an apocalyptic number.

It is an amenable number.

40242721 is a deficient number, since it is larger than the sum of its proper divisors (1).

40242721 is an equidigital number, since it uses as much as digits as its factorization.

40242721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 40242721 is about 6343.7150787216. The cubic root of 40242721 is about 342.6855399772.

Adding to 40242721 its reverse (12724204), we get a palindrome (52966925).

The spelling of 40242721 in words is "forty million, two hundred forty-two thousand, seven hundred twenty-one".