166821057 has 12 divisors (see below), whose sum is σ = 259499604. Its totient is φ = 102659040.

The previous prime is 166820999. The next prime is 166821059. The reversal of 166821057 is 750128661.

It can be written as a sum of positive squares in 2 ways, for example, as 100821681 + 65999376 = 10041^2 + 8124^2 .

It is a de Polignac number, because none of the positive numbers 2^k-166821057 is a prime.

It is not an unprimeable number, because it can be changed into a prime (166821059) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 712794 + ... + 713027.

It is an arithmetic number, because the mean of its divisors is an integer number (21624967).

Almost surely, 2^166821057 is an apocalyptic number.

It is an amenable number.

166821057 is a deficient number, since it is larger than the sum of its proper divisors (92678547).

166821057 is a wasteful number, since it uses less digits than its factorization.

166821057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1425840 (or 1425837 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 166821057 is about 12915.9226151290. The cubic root of 166821057 is about 550.4910842550.

The spelling of 166821057 in words is "one hundred sixty-six million, eight hundred twenty-one thousand, fifty-seven".