166940821 has 4 divisors (see below), whose sum is σ = 175727200. Its totient is φ = 158154444.

The previous prime is 166940819. The next prime is 166940827. The reversal of 166940821 is 128049661.

It is a happy number.

166940821 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.

It is a cyclic number.

It is not a de Polignac number, because 166940821 - 2¹ = 166940819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166940827) 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, 4393161 + ... + 4393198.

It is an arithmetic number, because the mean of its divisors is an integer number (43931800).

Almost surely, 2^166940821 is an apocalyptic number.

It is an amenable number.

166940821 is a deficient number, since it is larger than the sum of its proper divisors (8786379).

166940821 is an equidigital number, since it uses as much as digits as its factorization.

166940821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8786378.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 166940821 is about 12920.5580761823. The cubic root of 166940821 is about 550.6227887381.

It can be divided in two parts, 166940 and 821, that added together give a palindrome (167761).

The spelling of 166940821 in words is "one hundred sixty-six million, nine hundred forty thousand, eight hundred twenty-one".