166420221 has 16 divisors (see below), whose sum is σ = 254807040. Its totient is φ = 95551920.

The previous prime is 166420201. The next prime is 166420273. The reversal of 166420221 is 122024661.

It is not a de Polignac number, because 166420221 - 2¹⁵ = 166387453 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 166420191 and 166420200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166420201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 132085 + ... + 133338.

It is an arithmetic number, because the mean of its divisors is an integer number (15925440).

Almost surely, 2^166420221 is an apocalyptic number.

166420221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

166420221 is a deficient number, since it is larger than the sum of its proper divisors (88386819).

166420221 is a wasteful number, since it uses less digits than its factorization.

166420221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265456.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 166420221 is about 12900.3961567077. The cubic root of 166420221 is about 550.0498257891.

Adding to 166420221 its reverse (122024661), we get a palindrome (288444882).

The spelling of 166420221 in words is "one hundred sixty-six million, four hundred twenty thousand, two hundred twenty-one".