166810621 has 8 divisors (see below), whose sum is σ = 169400504. Its totient is φ = 164229120.

The previous prime is 166810607. The next prime is 166810667. The reversal of 166810621 is 126018661.

It can be written as a sum of positive squares in 4 ways, for example, as 10310521 + 156500100 = 3211^2 + 12510^2 .

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 166810621 - 2⁹ = 166810109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166810601) 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, 46525 + ... + 49981.

It is an arithmetic number, because the mean of its divisors is an integer number (21175063).

Almost surely, 2^166810621 is an apocalyptic number.

It is an amenable number.

166810621 is a deficient number, since it is larger than the sum of its proper divisors (2589883).

166810621 is an equidigital number, since it uses as much as digits as its factorization.

166810621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4191.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 166810621 is about 12915.5186113450. The cubic root of 166810621 is about 550.4796047994.

The spelling of 166810621 in words is "one hundred sixty-six million, eight hundred ten thousand, six hundred twenty-one".