161651 has 6 divisors (see below), whose sum is σ = 188100. Its totient is φ = 138516.

The previous prime is 161641. The next prime is 161659. The reversal of 161651 is 156161.

It is a happy number.

It is not a de Polignac number, because 161651 - 2¹⁰ = 160627 is a prime.

It is a super-2 number, since 2×161651² = 52262091602, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161659) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1601 + ... + 1698.

It is an arithmetic number, because the mean of its divisors is an integer number (31350).

2¹⁶¹⁶⁵¹ is an apocalyptic number.

161651 is a deficient number, since it is larger than the sum of its proper divisors (26449).

161651 is an equidigital number, since it uses as much as digits as its factorization.

161651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3313 (or 3306 counting only the distinct ones).

The product of its digits is 180, while the sum is 20.

The square root of 161651 is about 402.0584534617. The cubic root of 161651 is about 54.4744430295.

The spelling of 161651 in words is "one hundred sixty-one thousand, six hundred fifty-one".