1666721152 has 64 divisors (see below), whose sum is σ = 3365388000. Its totient is φ = 822169600.

The previous prime is 1666721143. The next prime is 1666721153. The reversal of 1666721152 is 2511276661.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666721153) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5359077 + ... + 5359387.

Almost surely, 2^1666721152 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1666721152, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1682694000).

1666721152 is an abundant number, since it is smaller than the sum of its proper divisors (1698666848).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1666721152 is a wasteful number, since it uses less digits than its factorization.

1666721152 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755 (or 743 counting only the distinct ones).

The product of its digits is 30240, while the sum is 37.

The square root of 1666721152 is about 40825.4963472583. The cubic root of 1666721152 is about 1185.6440212571.

The spelling of 1666721152 in words is "one billion, six hundred sixty-six million, seven hundred twenty-one thousand, one hundred fifty-two".