161801021 has 8 divisors (see below), whose sum is σ = 170735040. Its totient is φ = 153025312.

The previous prime is 161801011. The next prime is 161801041. The reversal of 161801021 is 120108161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161801021 - 2⁶ = 161800957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 161800984 and 161801002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161801011) 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, 37475 + ... + 41568.

It is an arithmetic number, because the mean of its divisors is an integer number (21341880).

Almost surely, 2^161801021 is an apocalyptic number.

It is an amenable number.

161801021 is a deficient number, since it is larger than the sum of its proper divisors (8934019).

161801021 is an equidigital number, since it uses as much as digits as its factorization.

161801021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79155.

The product of its (nonzero) digits is 96, while the sum is 20.

The square root of 161801021 is about 12720.1030263123. The cubic root of 161801021 is about 544.9128957671.

Adding to 161801021 its reverse (120108161), we get a palindrome (281909182).

The spelling of 161801021 in words is "one hundred sixty-one million, eight hundred one thousand, twenty-one".