1209717961 has 3 divisors (see below), whose sum is σ = 1209752743. Its totient is φ = 1209683180.

The previous prime is 1209717941. The next prime is 1209718009. The reversal of 1209717961 is 1697179021.

The square root of 1209717961 is 34781.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1697179021 = 2957 ⋅573953.

It can be written as a sum of positive squares in only one way, i.e., 413349561 + 796368400 = 20331^2 + 28220^2 .

It is not a de Polignac number, because 1209717961 - 2⁹ = 1209717449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1209717911) 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 in 2 ways as a sum of consecutive naturals, for example, 17391 + ... + 52171.

Almost surely, 2^1209717961 is an apocalyptic number.

1209717961 is the 34781-st square number.

1209717961 is the 17391-st centered octagonal number.

It is an amenable number.

1209717961 is a deficient number, since it is larger than the sum of its proper divisors (34782).

1209717961 is an frugal number, since it uses more digits than its factorization.

1209717961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69562 (or 34781 counting only the distinct ones).

The product of its (nonzero) digits is 47628, while the sum is 43.

The cubic root of 1209717961 is about 1065.5194365618.

The spelling of 1209717961 in words is "one billion, two hundred nine million, seven hundred seventeen thousand, nine hundred sixty-one".