161821500 has 48 divisors (see below), whose sum is σ = 471228576. Its totient is φ = 43152000.

The previous prime is 161821489. The next prime is 161821501. The reversal of 161821500 is 5128161.

161821500 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161821501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52441 + ... + 55440.

It is an arithmetic number, because the mean of its divisors is an integer number (9817262).

Almost surely, 2^161821500 is an apocalyptic number.

161821500 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161821500 is an abundant number, since it is smaller than the sum of its proper divisors (309407076).

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

161821500 is a wasteful number, since it uses less digits than its factorization.

161821500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107903 (or 107891 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 161821500 is about 12720.9079864607. The cubic root of 161821500 is about 544.9358844981.

Adding to 161821500 its reverse (5128161), we get a palindrome (166949661).

The spelling of 161821500 in words is "one hundred sixty-one million, eight hundred twenty-one thousand, five hundred".