1221760161 has 48 divisors (see below), whose sum is σ = 1894628736. Its totient is φ = 756822528.

The previous prime is 1221760157. The next prime is 1221760171. The reversal of 1221760161 is 1610671221.

It is a happy number.

It is not a de Polignac number, because 1221760161 - 2² = 1221760157 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221760151) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2821401 + ... + 2821833.

It is an arithmetic number, because the mean of its divisors is an integer number (39471432).

Almost surely, 2^1221760161 is an apocalyptic number.

It is an amenable number.

1221760161 is a deficient number, since it is larger than the sum of its proper divisors (672868575).

1221760161 is a wasteful number, since it uses less digits than its factorization.

1221760161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 822 (or 819 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 1221760161 is about 34953.6859429732. The cubic root of 1221760161 is about 1069.0433587224.

The spelling of 1221760161 in words is "one billion, two hundred twenty-one million, seven hundred sixty thousand, one hundred sixty-one".