161517820 has 24 divisors (see below), whose sum is σ = 350884800. Its totient is φ = 62379072.

The previous prime is 161517787. The next prime is 161517821. The reversal of 161517820 is 28715161.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161517821) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 138660 + ... + 139819.

It is an arithmetic number, because the mean of its divisors is an integer number (14620200).

Almost surely, 2^161517820 is an apocalyptic number.

161517820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161517820 is an abundant number, since it is smaller than the sum of its proper divisors (189366980).

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

161517820 is a wasteful number, since it uses less digits than its factorization.

161517820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278517 (or 278515 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 31.

The square root of 161517820 is about 12708.9661263220. The cubic root of 161517820 is about 544.5947889977.

The spelling of 161517820 in words is "one hundred sixty-one million, five hundred seventeen thousand, eight hundred twenty".