1005156721 has 2 divisors, whose sum is σ = 1005156722. Its totient is φ = 1005156720.

The previous prime is 1005156703. The next prime is 1005156749. The reversal of 1005156721 is 1276515001.

It is an a-pointer prime, because the next prime (1005156749) can be obtained adding 1005156721 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1004573025 + 583696 = 31695^2 + 764^2 .

It is a cyclic number.

It is not a de Polignac number, because 1005156721 - 2¹¹ = 1005154673 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1005156721.

It is not a weakly prime, because it can be changed into another prime (1005156521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 502578360 + 502578361.

It is an arithmetic number, because the mean of its divisors is an integer number (502578361).

Almost surely, 2^1005156721 is an apocalyptic number.

It is an amenable number.

1005156721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1005156721 is an equidigital number, since it uses as much as digits as its factorization.

1005156721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2100, while the sum is 28.

The square root of 1005156721 is about 31704.2066767172. The cubic root of 1005156721 is about 1001.7159607943.

The spelling of 1005156721 in words is "one billion, five million, one hundred fifty-six thousand, seven hundred twenty-one".