161821456 has 20 divisors (see below), whose sum is σ = 314054800. Its totient is φ = 80775072.

The previous prime is 161821433. The next prime is 161821459. The reversal of 161821456 is 654128161.

It is not an unprimeable number, because it can be changed into a prime (161821459) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1735 + ... + 18073.

It is an arithmetic number, because the mean of its divisors is an integer number (15702740).

Almost surely, 2^161821456 is an apocalyptic number.

161821456 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

161821456 is a deficient number, since it is larger than the sum of its proper divisors (152233344).

161821456 is a wasteful number, since it uses less digits than its factorization.

161821456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16966 (or 16960 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 161821456 is about 12720.9062570243. The cubic root of 161821456 is about 544.9358351079.

The spelling of 161821456 in words is "one hundred sixty-one million, eight hundred twenty-one thousand, four hundred fifty-six".