1666361421 has 12 divisors (see below), whose sum is σ = 2419440348. Its totient is φ = 1105150464.

The previous prime is 1666361407. The next prime is 1666361441. The reversal of 1666361421 is 1241636661.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 120692196 + 1545669225 = 10986^2 + 39315^2 .

It is not a de Polignac number, because 1666361421 - 2⁶ = 1666361357 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666361441) 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, 477930 + ... + 481403.

It is an arithmetic number, because the mean of its divisors is an integer number (201620029).

Almost surely, 2^1666361421 is an apocalyptic number.

It is an amenable number.

1666361421 is a deficient number, since it is larger than the sum of its proper divisors (753078927).

1666361421 is a wasteful number, since it uses less digits than its factorization.

1666361421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 959532 (or 959529 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 1666361421 is about 40821.0903945497. The cubic root of 1666361421 is about 1185.5587153262.

The spelling of 1666361421 in words is "one billion, six hundred sixty-six million, three hundred sixty-one thousand, four hundred twenty-one".