166521615 has 64 divisors (see below), whose sum is σ = 299765760. Its totient is φ = 78848640.

The previous prime is 166521533. The next prime is 166521617. The reversal of 166521615 is 516125661.

It is not a de Polignac number, because 166521615 - 2¹⁰ = 166520591 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166521617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1021524 + ... + 1021686.

It is an arithmetic number, because the mean of its divisors is an integer number (4683840).

Almost surely, 2^166521615 is an apocalyptic number.

166521615 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

166521615 is a deficient number, since it is larger than the sum of its proper divisors (133244145).

166521615 is a wasteful number, since it uses less digits than its factorization.

166521615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241 (or 215 counting only the distinct ones).

The product of its digits is 10800, while the sum is 33.

The square root of 166521615 is about 12904.3254376197. The cubic root of 166521615 is about 550.1615117948.

The spelling of 166521615 in words is "one hundred sixty-six million, five hundred twenty-one thousand, six hundred fifteen".