1664902476721 has 27 divisors (see below), whose sum is σ = 1876395828097. Its totient is φ = 1476115784000.

The previous prime is 1664902476703. The next prime is 1664902476737. The reversal of 1664902476721 is 1276742094661.

It is a happy number.

The square root of 1664902476721 is 1290311.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 389674329121 + 1275228147600 = 624239^2 + 1129260^2 .

It is not a de Polignac number, because 1664902476721 - 2¹¹ = 1664902474673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1664902476701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 581928831 + ... + 581931691.

Almost surely, 2^{1664902476721} is an apocalyptic number.

1664902476721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1664902476721 is the 1290311-st square number.

1664902476721 is the 645156-th centered octagonal number.

It is an amenable number.

1664902476721 is a deficient number, since it is larger than the sum of its proper divisors (211493351376).

1664902476721 is an frugal number, since it uses more digits than its factorization.

1664902476721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5826 (or 2913 counting only the distinct ones).

The product of its (nonzero) digits is 6096384, while the sum is 55.

The spelling of 1664902476721 in words is "one trillion, six hundred sixty-four billion, nine hundred two million, four hundred seventy-six thousand, seven hundred twenty-one".