1664855972515 has 4 divisors (see below), whose sum is σ = 1997827167024. Its totient is φ = 1331884778008.

The previous prime is 1664855972513. The next prime is 1664855972561. The reversal of 1664855972515 is 5152795584661.

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

It is a cyclic number.

It is not a de Polignac number, because 1664855972515 - 2¹ = 1664855972513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1664855972513) 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, 166485597247 + ... + 166485597256.

It is an arithmetic number, because the mean of its divisors is an integer number (499456791756).

Almost surely, 2^{1664855972515} is an apocalyptic number.

1664855972515 is a deficient number, since it is larger than the sum of its proper divisors (332971194509).

1664855972515 is an equidigital number, since it uses as much as digits as its factorization.

1664855972515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332971194508.

The product of its digits is 90720000, while the sum is 64.

The spelling of 1664855972515 in words is "one trillion, six hundred sixty-four billion, eight hundred fifty-five million, nine hundred seventy-two thousand, five hundred fifteen".