16661774641021 has 4 divisors (see below), whose sum is σ = 16723257204544. Its totient is φ = 16600292077500.

The previous prime is 16661774640997. The next prime is 16661774641073. The reversal of 16661774641021 is 12014647716661.

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 16661774641021 - 2⁷ = 16661774640893 is a prime.

It is a super-2 number, since 2×16661774641021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16661774641021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16661774641081) 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, 30741281355 + ... + 30741281896.

It is an arithmetic number, because the mean of its divisors is an integer number (4180814301136).

Almost surely, 2^{16661774641021} is an apocalyptic number.

It is an amenable number.

16661774641021 is a deficient number, since it is larger than the sum of its proper divisors (61482563523).

16661774641021 is an equidigital number, since it uses as much as digits as its factorization.

16661774641021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61482563522.

The product of its (nonzero) digits is 2032128, while the sum is 52.

The spelling of 16661774641021 in words is "sixteen trillion, six hundred sixty-one billion, seven hundred seventy-four million, six hundred forty-one thousand, twenty-one".