161561400 has 384 divisors, whose sum is σ = 674956800. Its totient is φ = 30873600.

The previous prime is 161561381. The next prime is 161561417. The reversal of 161561400 is 4165161.

It is a super-2 number, since 2×161561400² = 52204171939920000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 600466 + ... + 600734.

It is an arithmetic number, because the mean of its divisors is an integer number (1757700).

Almost surely, 2^161561400 is an apocalyptic number.

161561400 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 161561400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (337478400).

161561400 is an abundant number, since it is smaller than the sum of its proper divisors (513395400).

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

161561400 is a wasteful number, since it uses less digits than its factorization.

161561400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319 (or 310 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 161561400 is about 12710.6805482633. The cubic root of 161561400 is about 544.6437646189.

The spelling of 161561400 in words is "one hundred sixty-one million, five hundred sixty-one thousand, four hundred".