161747221 has 4 divisors (see below), whose sum is σ = 161774272. Its totient is φ = 161720172.

The previous prime is 161747219. The next prime is 161747233. The reversal of 161747221 is 122747161.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122747161 = 739 ⋅166099.

It is a cyclic number.

It is not a de Polignac number, because 161747221 - 2¹ = 161747219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161747251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141 + ... + 17986.

It is an arithmetic number, because the mean of its divisors is an integer number (40443568).

Almost surely, 2^161747221 is an apocalyptic number.

It is an amenable number.

161747221 is a deficient number, since it is larger than the sum of its proper divisors (27051).

161747221 is an equidigital number, since it uses as much as digits as its factorization.

161747221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27050.

The product of its digits is 4704, while the sum is 31.

The square root of 161747221 is about 12717.9880877441. The cubic root of 161747221 is about 544.8524932564.

The spelling of 161747221 in words is "one hundred sixty-one million, seven hundred forty-seven thousand, two hundred twenty-one".