172161920 has 128 divisors (see below), whose sum is σ = 477066240. Its totient is φ = 58189824.

The previous prime is 172161919. The next prime is 172161931. The reversal of 172161920 is 29161271.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 371609 + ... + 372071.

It is an arithmetic number, because the mean of its divisors is an integer number (3727080).

Almost surely, 2^172161920 is an apocalyptic number.

172161920 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 172161920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (238533120).

172161920 is an abundant number, since it is smaller than the sum of its proper divisors (304904320).

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

172161920 is an equidigital number, since it uses as much as digits as its factorization.

172161920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 572 (or 560 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 29.

The square root of 172161920 is about 13121.0487385727. The cubic root of 172161920 is about 556.3042345806.

The spelling of 172161920 in words is "one hundred seventy-two million, one hundred sixty-one thousand, nine hundred twenty".