166821137 has 32 divisors (see below), whose sum is σ = 208128000. Its totient is φ = 133358400.

The previous prime is 166821131. The next prime is 166821167. The reversal of 166821137 is 731128661.

It is not a de Polignac number, because 166821137 - 2¹⁴ = 166804753 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 166821097 and 166821106.

It is not an unprimeable number, because it can be changed into a prime (166821131) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 308087 + ... + 308627.

It is an arithmetic number, because the mean of its divisors is an integer number (6504000).

Almost surely, 2^166821137 is an apocalyptic number.

It is an amenable number.

166821137 is a deficient number, since it is larger than the sum of its proper divisors (41306863).

166821137 is an equidigital number, since it uses as much as digits as its factorization.

166821137 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 622 (or 608 counting only the distinct ones).

The product of its digits is 12096, while the sum is 35.

The square root of 166821137 is about 12915.9257120812. The cubic root of 166821137 is about 550.4911722520.

Adding to 166821137 its reverse (731128661), we get a palindrome (897949798).

The spelling of 166821137 in words is "one hundred sixty-six million, eight hundred twenty-one thousand, one hundred thirty-seven".