166915021 has 24 divisors (see below), whose sum is σ = 210560280. Its totient is φ = 131144832.

The previous prime is 166915009. The next prime is 166915037. The reversal of 166915021 is 120519661.

It can be written as a sum of positive squares in 4 ways, for example, as 1920996 + 164994025 = 1386^2 + 12845^2 .

It is not a de Polignac number, because 166915021 - 2¹¹ = 166912973 is a prime.

166915021 is a modest number, since divided by 15021 gives 1669 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166915051) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 99175 + ... + 100843.

It is an arithmetic number, because the mean of its divisors is an integer number (8773345).

Almost surely, 2^166915021 is an apocalyptic number.

It is an amenable number.

166915021 is a deficient number, since it is larger than the sum of its proper divisors (43645259).

166915021 is a wasteful number, since it uses less digits than its factorization.

166915021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1853 (or 1846 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 166915021 is about 12919.5596287180. The cubic root of 166915021 is about 550.5944218000.

It can be divided in two parts, 16691 and 5021, that added together give a palindrome (21712).

The spelling of 166915021 in words is "one hundred sixty-six million, nine hundred fifteen thousand, twenty-one".