1666658772 has 36 divisors (see below), whose sum is σ = 4254664596. Its totient is φ = 550051200.

The previous prime is 1666658771. The next prime is 1666658779. The reversal of 1666658772 is 2778566661.

It can be written as a sum of positive squares in 2 ways, for example, as 1561514256 + 105144516 = 39516^2 + 10254^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666658771) 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, 225553 + ... + 232824.

Almost surely, 2^1666658772 is an apocalyptic number.

1666658772 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1666658772 is an abundant number, since it is smaller than the sum of its proper divisors (2588005824).

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

1666658772 is a wasteful number, since it uses less digits than its factorization.

1666658772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458488 (or 458483 counting only the distinct ones).

The product of its digits is 5080320, while the sum is 54.

The square root of 1666658772 is about 40824.7323567467. The cubic root of 1666658772 is about 1185.6292294613.

The spelling of 1666658772 in words is "one billion, six hundred sixty-six million, six hundred fifty-eight thousand, seven hundred seventy-two".