166415521 has 4 divisors (see below), whose sum is σ = 166441392. Its totient is φ = 166389652.

The previous prime is 166415519. The next prime is 166415539. The reversal of 166415521 is 125514661.

166415521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 166415521 - 2¹ = 166415519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166415321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5046 + ... + 18928.

It is an arithmetic number, because the mean of its divisors is an integer number (41610348).

Almost surely, 2^166415521 is an apocalyptic number.

It is an amenable number.

166415521 is a deficient number, since it is larger than the sum of its proper divisors (25871).

166415521 is a wasteful number, since it uses less digits than its factorization.

166415521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25870.

The product of its digits is 7200, while the sum is 31.

The square root of 166415521 is about 12900.2139904732. The cubic root of 166415521 is about 550.0446476152.

The spelling of 166415521 in words is "one hundred sixty-six million, four hundred fifteen thousand, five hundred twenty-one".