161620 has 12 divisors (see below), whose sum is σ = 339444. Its totient is φ = 64640.

The previous prime is 161611. The next prime is 161627. The reversal of 161620 is 26161.

161620 = T₁₁₇ + T₁₁₈ + ... + T₁₃₆.

It can be written as a sum of positive squares in 2 ways, for example, as 56644 + 104976 = 238^2 + 324^2 .

It is a super-2 number, since 2×161620² = 52242048800, which contains 22 as substring.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 161594 and 161603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161627) by changing a digit.

161620 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4021 + ... + 4060.

It is an arithmetic number, because the mean of its divisors is an integer number (28287).

2¹⁶¹⁶²⁰ is an apocalyptic number.

161620 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161620 is an abundant number, since it is smaller than the sum of its proper divisors (177824).

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

161620 is a wasteful number, since it uses less digits than its factorization.

161620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8090 (or 8088 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 161620 is about 402.0199000050. The cubic root of 161620 is about 54.4709605978.

Subtracting from 161620 its sum of digits (16), we obtain a square (161604 = 402²).

Adding to 161620 its reverse (26161), we get a palindrome (187781).

The spelling of 161620 in words is "one hundred sixty-one thousand, six hundred twenty".