161821222 has 4 divisors (see below), whose sum is σ = 242731836. Its totient is φ = 80910610.

The previous prime is 161821139. The next prime is 161821223. The reversal of 161821222 is 222128161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 222128161 = 1171 ⋅189691.

It is a super-2 number, since 2×161821222² = 52372215779146568, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161821223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40455304 + ... + 40455307.

It is an arithmetic number, because the mean of its divisors is an integer number (60682959).

Almost surely, 2^161821222 is an apocalyptic number.

161821222 is a deficient number, since it is larger than the sum of its proper divisors (80910614).

161821222 is an equidigital number, since it uses as much as digits as its factorization.

161821222 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80910613.

The product of its digits is 768, while the sum is 25.

The square root of 161821222 is about 12720.8970595631. The cubic root of 161821222 is about 544.9355724417.

Adding to 161821222 its reverse (222128161), we get a palindrome (383949383).

The spelling of 161821222 in words is "one hundred sixty-one million, eight hundred twenty-one thousand, two hundred twenty-two".