1666443155 has 16 divisors (see below), whose sum is σ = 2206086624. Its totient is φ = 1200587520.

The previous prime is 1666443101. The next prime is 1666443157. The reversal of 1666443155 is 5513446661.

It is not a de Polignac number, because 1666443155 - 2⁶ = 1666443091 is a prime.

It is a super-4 number, since 4×1666443155⁴ (a number of 38 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666443157) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 309989 + ... + 315318.

It is an arithmetic number, because the mean of its divisors is an integer number (137880414).

Almost surely, 2^1666443155 is an apocalyptic number.

1666443155 is a deficient number, since it is larger than the sum of its proper divisors (539643469).

1666443155 is a wasteful number, since it uses less digits than its factorization.

1666443155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 625366.

The product of its digits is 259200, while the sum is 41.

The square root of 1666443155 is about 40822.0915069280. The cubic root of 1666443155 is about 1185.5780986506.

The spelling of 1666443155 in words is "one billion, six hundred sixty-six million, four hundred forty-three thousand, one hundred fifty-five".