1221953684161 has 12 divisors (see below), whose sum is σ = 1431682638960. Its totient is φ = 1039853694600.

The previous prime is 1221953684129. The next prime is 1221953684167. The reversal of 1221953684161 is 1614863591221.

It is not a de Polignac number, because 1221953684161 - 2⁵ = 1221953684129 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is not an unprimeable number, because it can be changed into a prime (1221953684167) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 89697615 + ... + 89711236.

It is an arithmetic number, because the mean of its divisors is an integer number (119306886580).

Almost surely, 2^{1221953684161} is an apocalyptic number.

It is an amenable number.

1221953684161 is a deficient number, since it is larger than the sum of its proper divisors (209728954799).

1221953684161 is a wasteful number, since it uses less digits than its factorization.

1221953684161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179409004 (or 179408997 counting only the distinct ones).

The product of its digits is 622080, while the sum is 49.

The spelling of 1221953684161 in words is "one trillion, two hundred twenty-one billion, nine hundred fifty-three million, six hundred eighty-four thousand, one hundred sixty-one".