240721981 has 2 divisors, whose sum is σ = 240721982. Its totient is φ = 240721980.

The previous prime is 240721967. The next prime is 240721997. The reversal of 240721981 is 189127042.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 122456356 + 118265625 = 11066^2 + 10875^2 .

It is a cyclic number.

It is not a de Polignac number, because 240721981 - 2²¹ = 238624829 is a prime.

It is a super-2 number, since 2×240721981² = 115894144273128722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (240721931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 120360990 + 120360991.

It is an arithmetic number, because the mean of its divisors is an integer number (120360991).

Almost surely, 2^240721981 is an apocalyptic number.

It is an amenable number.

240721981 is a deficient number, since it is larger than the sum of its proper divisors (1).

240721981 is an equidigital number, since it uses as much as digits as its factorization.

240721981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 34.

The square root of 240721981 is about 15515.2177232548. The cubic root of 240721981 is about 622.0690337043.

The spelling of 240721981 in words is "two hundred forty million, seven hundred twenty-one thousand, nine hundred eighty-one".