161638400 has 288 divisors, whose sum is σ = 511842240. Its totient is φ = 49152000.

The previous prime is 161638381. The next prime is 161638409. The reversal of 161638400 is 4836161.

It is a super-3 number, since 3×161638400³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (161638409) 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, 3942380 + ... + 3942420.

It is an arithmetic number, because the mean of its divisors is an integer number (1777230).

Almost surely, 2^161638400 is an apocalyptic number.

161638400 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 161638400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (255921120).

161638400 is an abundant number, since it is smaller than the sum of its proper divisors (350203840).

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

161638400 is a wasteful number, since it uses less digits than its factorization.

161638400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 66 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 161638400 is about 12713.7091362041. The cubic root of 161638400 is about 544.7302764325.

It can be divided in two parts, 16 and 1638400, that multiplied together give a square (26214400 = 5120²).

The spelling of 161638400 in words is "one hundred sixty-one million, six hundred thirty-eight thousand, four hundred".