2157512666 has 4 divisors (see below), whose sum is σ = 3236269002. Its totient is φ = 1078756332.

The previous prime is 2157512639. The next prime is 2157512671. The reversal of 2157512666 is 6662157512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1812630625 + 344882041 = 42575^2 + 18571^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 539378165 + ... + 539378168.

Almost surely, 2^2157512666 is an apocalyptic number.

2157512666 is a deficient number, since it is larger than the sum of its proper divisors (1078756336).

2157512666 is a wasteful number, since it uses less digits than its factorization.

2157512666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1078756335.

The product of its digits is 151200, while the sum is 41.

The square root of 2157512666 is about 46449.0329931636. The cubic root of 2157512666 is about 1292.1644383770.

The spelling of 2157512666 in words is "two billion, one hundred fifty-seven million, five hundred twelve thousand, six hundred sixty-six".