1217151705721 has 10 divisors (see below), whose sum is σ = 1419925836922. Its totient is φ = 1043272888560.

The previous prime is 1217151705631. The next prime is 1217151705727. The reversal of 1217151705721 is 1275071517121.

It can be written as a sum of positive squares in only one way, i.e., 1168855050496 + 48296655225 = 1081136^2 + 219765^2 .

It is not a de Polignac number, because 1217151705721 - 2⁷ = 1217151705593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1217151705727) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 253465260 + ... + 253470061.

Almost surely, 2^{1217151705721} is an apocalyptic number.

It is an amenable number.

1217151705721 is a deficient number, since it is larger than the sum of its proper divisors (202774131201).

1217151705721 is an frugal number, since it uses more digits than its factorization.

1217151705721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506935349 (or 506935328 counting only the distinct ones).

The product of its (nonzero) digits is 34300, while the sum is 40.

The spelling of 1217151705721 in words is "one trillion, two hundred seventeen billion, one hundred fifty-one million, seven hundred five thousand, seven hundred twenty-one".