166211021 has 8 divisors (see below), whose sum is σ = 170235000. Its totient is φ = 162220032.

The previous prime is 166211011. The next prime is 166211027. The reversal of 166211021 is 120112661.

It can be written as a sum of positive squares in 4 ways, for example, as 27678121 + 138532900 = 5261^2 + 11770^2 .

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 166211021 - 2²² = 162016717 is a prime.

It is a super-2 number, since 2×166211021² = 55252207003724882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 166210984 and 166211002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166211027) 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, 2105 + ... + 18353.

It is an arithmetic number, because the mean of its divisors is an integer number (21279375).

Almost surely, 2^166211021 is an apocalyptic number.

It is an amenable number.

166211021 is a deficient number, since it is larger than the sum of its proper divisors (4023979).

166211021 is a wasteful number, since it uses less digits than its factorization.

166211021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16495.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 166211021 is about 12892.2853288313. The cubic root of 166211021 is about 549.8192474909.

Adding to 166211021 its reverse (120112661), we get a palindrome (286323682).

The spelling of 166211021 in words is "one hundred sixty-six million, two hundred eleven thousand, twenty-one".