161221889851 has 8 divisors (see below), whose sum is σ = 176330559600. Its totient is φ = 146188575840.

The previous prime is 161221889849. The next prime is 161221889867. The reversal of 161221889851 is 158988122161.

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 161221889851 - 2¹ = 161221889849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161221889891) 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, 18834456 + ... + 18843013.

It is an arithmetic number, because the mean of its divisors is an integer number (22041319950).

Almost surely, 2^161221889851 is an apocalyptic number.

161221889851 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

161221889851 is a deficient number, since it is larger than the sum of its proper divisors (15108669749).

161221889851 is a wasteful number, since it uses less digits than its factorization.

161221889851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37677869.

The product of its digits is 552960, while the sum is 52.

The spelling of 161221889851 in words is "one hundred sixty-one billion, two hundred twenty-one million, eight hundred eighty-nine thousand, eight hundred fifty-one".