161720444400 has 120 divisors (see below), whose sum is σ = 521826367344. Its totient is φ = 42810624000.

The previous prime is 161720444383. The next prime is 161720444401. The reversal of 161720444400 is 4444027161.

It is a tau number, because it is divible by the number of its divisors (120).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161720444401) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 327451 + ... + 656250.

Almost surely, 2^161720444400 is an apocalyptic number.

161720444400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161720444400 is an abundant number, since it is smaller than the sum of its proper divisors (360105922944).

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

161720444400 is a wasteful number, since it uses less digits than its factorization.

161720444400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 983859 (or 983848 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 33.

The spelling of 161720444400 in words is "one hundred sixty-one billion, seven hundred twenty million, four hundred forty-four thousand, four hundred".