161221773 has 8 divisors (see below), whose sum is σ = 217552608. Its totient is φ = 106186064.

The previous prime is 161221771. The next prime is 161221843. The reversal of 161221773 is 377122161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161221773 - 2¹ = 161221771 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161221773.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161221771) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 323490 + ... + 323987.

It is an arithmetic number, because the mean of its divisors is an integer number (27194076).

Almost surely, 2^161221773 is an apocalyptic number.

It is an amenable number.

161221773 is a deficient number, since it is larger than the sum of its proper divisors (56330835).

161221773 is an equidigital number, since it uses as much as digits as its factorization.

161221773 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 647563.

The product of its digits is 3528, while the sum is 30.

The square root of 161221773 is about 12697.3136135168. The cubic root of 161221773 is about 544.2618551296.

The spelling of 161221773 in words is "one hundred sixty-one million, two hundred twenty-one thousand, seven hundred seventy-three".