1666432401 has 4 divisors (see below), whose sum is σ = 2221909872. Its totient is φ = 1110954932.

The previous prime is 1666432321. The next prime is 1666432421. The reversal of 1666432401 is 1042346661.

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 a de Polignac number, because none of the positive numbers 2^k-1666432401 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666432421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 277738731 + ... + 277738736.

It is an arithmetic number, because the mean of its divisors is an integer number (555477468).

Almost surely, 2^1666432401 is an apocalyptic number.

It is an amenable number.

1666432401 is a deficient number, since it is larger than the sum of its proper divisors (555477471).

1666432401 is an equidigital number, since it uses as much as digits as its factorization.

1666432401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 555477470.

The product of its (nonzero) digits is 20736, while the sum is 33.

The square root of 1666432401 is about 40821.9597888195. The cubic root of 1666432401 is about 1185.5755483617.

The spelling of 1666432401 in words is "one billion, six hundred sixty-six million, four hundred thirty-two thousand, four hundred one".