1209705217956 has 243 divisors, whose sum is σ = 3342188769283. Its totient is φ = 368851061760.

The previous prime is 1209705217927. The next prime is 1209705217961. The reversal of 1209705217956 is 6597125079021.

It is a happy number.

The square root of 1209705217956 is 1099866.

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

1209705217956 is a `hidden beast` number, since 1 + 20 + 9 + 7 + 0 + 521 + 7 + 95 + 6 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 85223124900 + 1124482093056 = 291930^2 + 1060416^2 .

It is a Duffinian number.

It is an unprimeable number.

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 in 80 ways as a sum of consecutive naturals, for example, 4599639481 + ... + 4599639743.

Almost surely, 2^{1209705217956} is an apocalyptic number.

1209705217956 is the 1099866-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1209705217956

1209705217956 is an abundant number, since it is smaller than the sum of its proper divisors (2132483551327).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1209705217956 is a wasteful number, since it uses less digits than its factorization.

1209705217956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 652 (or 326 counting only the distinct ones).

The product of its (nonzero) digits is 2381400, while the sum is 54.

The spelling of 1209705217956 in words is "one trillion, two hundred nine billion, seven hundred five million, two hundred seventeen thousand, nine hundred fifty-six".