161221132800 has 1350 divisors, whose sum is σ = 727092862353. Its totient is φ = 34015887360.

The previous prime is 161221132789. The next prime is 161221132823. The reversal of 161221132800 is 8231122161.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

161221132800 is a `hidden beast` number, since 1 + 612 + 2 + 11 + 32 + 8 + 0 + 0 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 102533163264 + 58687969536 = 320208^2 + 242256^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=283920.

It is a super-2 number, since 2×161221132800² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 12401625594 + ... + 12401625606.

Almost surely, 2^161221132800 is an apocalyptic number.

161221132800 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 161221132800

161221132800 is an abundant number, since it is smaller than the sum of its proper divisors (565871729553).

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

161221132800 is an frugal number, since it uses more digits than its factorization.

161221132800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100 (or 30 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

Multiplying 161221132800 by its product of nonzero digits (1152), we get a square (185726744985600 = 13628160²).

161221132800 divided by its product of nonzero digits (1152) gives a square (139948900 = 11830²).

Adding to 161221132800 its reverse (8231122161), we get a palindrome (169452254961).

The spelling of 161221132800 in words is "one hundred sixty-one billion, two hundred twenty-one million, one hundred thirty-two thousand, eight hundred".