161221012 has 6 divisors (see below), whose sum is σ = 282136778. Its totient is φ = 80610504.

The previous prime is 161221003. The next prime is 161221069. The reversal of 161221012 is 210122161.

It can be written as a sum of positive squares in only one way, i.e., 159668496 + 1552516 = 12636^2 + 1246^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20152623 + ... + 20152630.

Almost surely, 2^161221012 is an apocalyptic number.

It is an amenable number.

161221012 is a deficient number, since it is larger than the sum of its proper divisors (120915766).

161221012 is a wasteful number, since it uses less digits than its factorization.

161221012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40305257 (or 40305255 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 161221012 is about 12697.2836465127. The cubic root of 161221012 is about 544.2609987855.

Adding to 161221012 its reverse (210122161), we get a palindrome (371343173).

The spelling of 161221012 in words is "one hundred sixty-one million, two hundred twenty-one thousand, twelve".