161212900000 has 144 divisors (see below), whose sum is σ = 398812708728. Its totient is φ = 64143360000.

The previous prime is 161212899977. The next prime is 161212900001. The reversal of 161212900000 is 9212161.

It can be written as a sum of positive squares in 12 ways, for example, as 83199941136 + 78012958864 = 288444^2 + 279308^2 .

It is not an unprimeable number, because it can be changed into a prime (161212900001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19295824 + ... + 19304176.

Almost surely, 2^161212900000 is an apocalyptic number.

161212900000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161212900000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (199406354364).

161212900000 is an abundant number, since it is smaller than the sum of its proper divisors (237599808728).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161212900000 is an frugal number, since it uses more digits than its factorization.

161212900000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8581 (or 8553 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 22.

The spelling of 161212900000 in words is "one hundred sixty-one billion, two hundred twelve million, nine hundred thousand".