1221724342161 has 6 divisors (see below), whose sum is σ = 1764712938690. Its totient is φ = 814482894768.

The previous prime is 1221724342159. The next prime is 1221724342177. The reversal of 1221724342161 is 1612434271221.

1221724342161 is a `hidden beast` number, since 1 + 2 + 2 + 1 + 7 + 2 + 434 + 216 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1220538848400 + 1185493761 = 1104780^2 + 34431^2 .

It is not a de Polignac number, because 1221724342161 - 2¹ = 1221724342159 is a prime.

It is a super-2 number, since 2×1221724342161² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1221724352161) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 67873574556 + ... + 67873574573.

It is an arithmetic number, because the mean of its divisors is an integer number (294118823115).

Almost surely, 2^{1221724342161} is an apocalyptic number.

It is an amenable number.

1221724342161 is a deficient number, since it is larger than the sum of its proper divisors (542988596529).

1221724342161 is a wasteful number, since it uses less digits than its factorization.

1221724342161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135747149135 (or 135747149132 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The spelling of 1221724342161 in words is "one trillion, two hundred twenty-one billion, seven hundred twenty-four million, three hundred forty-two thousand, one hundred sixty-one".