161221001011 has 16 divisors (see below), whose sum is σ = 186253337088. Its totient is φ = 136691913600.

The previous prime is 161221000991. The next prime is 161221001047. The reversal of 161221001011 is 110100122161.

161221001011 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 161221001011 - 2³¹ = 159073517363 is a prime.

It is a super-2 number, since 2×161221001011² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161221001611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 508296 + ... + 762106.

It is an arithmetic number, because the mean of its divisors is an integer number (11640833568).

Almost surely, 2^161221001011 is an apocalyptic number.

161221001011 is a deficient number, since it is larger than the sum of its proper divisors (25032336077).

161221001011 is a wasteful number, since it uses less digits than its factorization.

161221001011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254802.

The product of its (nonzero) digits is 24, while the sum is 16.

Adding to 161221001011 its reverse (110100122161), we get a palindrome (271321123172).

The spelling of 161221001011 in words is "one hundred sixty-one billion, two hundred twenty-one million, one thousand, eleven".