161172020 has 12 divisors (see below), whose sum is σ = 338461284. Its totient is φ = 64468800.

The previous prime is 161171981. The next prime is 161172023. The reversal of 161172020 is 20271161.

It can be written as a sum of positive squares in 2 ways, for example, as 42667024 + 118504996 = 6532^2 + 10886^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 8058601 = 161172020 / (1 + 6 + 1 + 1 + 7 + 2 + 0 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 161171983 and 161172001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161172023) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 4029281 + ... + 4029320.

It is an arithmetic number, because the mean of its divisors is an integer number (28205107).

Almost surely, 2^161172020 is an apocalyptic number.

161172020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161172020 is an abundant number, since it is smaller than the sum of its proper divisors (177289264).

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

161172020 is a wasteful number, since it uses less digits than its factorization.

161172020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8058610 (or 8058608 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 161172020 is about 12695.3542683928. The cubic root of 161172020 is about 544.2058630107.

The spelling of 161172020 in words is "one hundred sixty-one million, one hundred seventy-two thousand, twenty".