166603821 has 4 divisors (see below), whose sum is σ = 222138432. Its totient is φ = 111069212.

The previous prime is 166603813. The next prime is 166603823. The reversal of 166603821 is 128306661.

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.

It is a cyclic number.

It is not a de Polignac number, because 166603821 - 2³ = 166603813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166603823) 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, 27767301 + ... + 27767306.

It is an arithmetic number, because the mean of its divisors is an integer number (55534608).

Almost surely, 2^166603821 is an apocalyptic number.

It is an amenable number.

166603821 is a deficient number, since it is larger than the sum of its proper divisors (55534611).

166603821 is an equidigital number, since it uses as much as digits as its factorization.

166603821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55534610.

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 166603821 is about 12907.5102556612. The cubic root of 166603821 is about 550.2520288467.

The spelling of 166603821 in words is "one hundred sixty-six million, six hundred three thousand, eight hundred twenty-one".