1151721209 has 2 divisors, whose sum is σ = 1151721210. Its totient is φ = 1151721208.

The previous prime is 1151721203. The next prime is 1151721211. The reversal of 1151721209 is 9021271511.

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., 1021122025 + 130599184 = 31955^2 + 11428^2 .

It is a cyclic number.

It is not a de Polignac number, because 1151721209 - 2¹² = 1151717113 is a prime.

It is a Sophie Germain prime.

Together with 1151721211, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1151721203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 575860604 + 575860605.

It is an arithmetic number, because the mean of its divisors is an integer number (575860605).

Almost surely, 2^1151721209 is an apocalyptic number.

It is an amenable number.

1151721209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1151721209 is an equidigital number, since it uses as much as digits as its factorization.

1151721209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1260, while the sum is 29.

The square root of 1151721209 is about 33937.0182691409. The cubic root of 1151721209 is about 1048.2119861486.

The spelling of 1151721209 in words is "one billion, one hundred fifty-one million, seven hundred twenty-one thousand, two hundred nine".