161781447828 has 192 divisors, whose sum is σ = 508032000000. Its totient is φ = 38697523200.

The previous prime is 161781447823. The next prime is 161781447833. The reversal of 161781447828 is 828744187161.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (161781447823) and next prime (161781447833).

It is a super-2 number, since 2×161781447828² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161781447823) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5161548 + ... + 5192796.

It is an arithmetic number, because the mean of its divisors is an integer number (2646000000).

Almost surely, 2^161781447828 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161781447828, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (254016000000).

161781447828 is an abundant number, since it is smaller than the sum of its proper divisors (346250552172).

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

161781447828 is a wasteful number, since it uses less digits than its factorization.

161781447828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31718 (or 31716 counting only the distinct ones).

The product of its digits is 4816896, while the sum is 57.

The spelling of 161781447828 in words is "one hundred sixty-one billion, seven hundred eighty-one million, four hundred forty-seven thousand, eight hundred twenty-eight".